MAIN  HBRARY.AG'RlCL»L.TUR*foef»T. 


BIOLOGY 
LIBRARY 


HOG  CHOLERA 


THE  MACMILLAN   COMPANY 

NEW  YORK   •    BOSTON   •     CHICAGO   •    DALLAS 
ATLANTA   •    SAN  FRANCISCO 

MACMILLAN  &  CO.,  LIMITED 

LONDON   •    BOMBAY   •    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  LTD. 

TORONTO 


HOG     CHOLERA 

ITS 

NATURE  AND  CONTROL 


BY 

RAYMOND  R.  £IRCH,  B.S.,  D.V.M.,  Pn.D. 

PROFESSOR  IN   CHARGE   OF  THE    NEW   YORK   STATE   VETERINARY 

COLLEGE    EXPERIMENT    STATION    AT   CORNELL 

UNIVERSITY,    ITHACA,    NEW    YORK 


gotft 

THE  MACMILLAN  COMPANY 
1922 

All  rights  reserved 


PRINTED  IN   THE  UNITED   STATES   OF  AMERICA 


COPYRIGHT,  1922, 
BT  THE  MACMILLAN  COMPANY. 

Set  up  and  printed.     Published  September,  1922. 

. 


Press  of 

J.  J.  Little  &  Ives  Company 
New  York,  U.  S.  A. 


PREFACE 

My  object  in  preparing  this  book  has  been  to  place 
in  the  hands  of  those  who  handle  hog  cholera  definite 
and  authoritative  information  regarding  the  disease. 
There  are  abundant  publications  dealing  with  hog 
cholera  but  for  the  most  part  they  consist  of  technical 
papers  covering  certain  restricted  phases  of  the  disease, 
or  of  attempts  to  circumscribe  the  entire  subject  in  the 
scope  of  a  few  pages.  Neither  meets  the  needs  of  the 
man  who  must  handle  hog  cholera  in  the  field.  More- 
over these  publications  appear  as  bulletins  or  as  special 
papers  in  technical  journals,  and  usually  they  are  not 
at  the  veterinarian's  command  at  the  time  he  needs 
them. 

We  are  rapidly  discarding  the  old  belief  that  any  one 
who  can  use  a  hypodermic  syringe  can  cope  with  hog 
cholera.  Questions  constantly  arise  regarding  diagnosis, 
complications,  when  or  whether  to  immunize,  which 
method  to  use,  the  subsequent  care  of  the  herd,  the 
handling  of  young  pigs,  slaughtering  from  infected 
herds  under  inspection,  and  many  other  individual  prob- 
lems. 

The  effective  handling  of  hog  cholera,  like  the  handling 
of  other  diseases,  is  founded  on  exact  knowledge  of  tlie 
malady  itself,  but  hog  cholera  differs  from  other  in- 
fectious diseases  in  that  preventive  vaccination  against 
it  has  served  to  open  the  new  field  of  swine  practice. 

v 

498438 


VI  PREFACE 

The  result  is  that  there  are  many  veterinarians  who 
will  not  attempt  to  cope  with  the  disease,  or  who, 
making  the  attempt,  feel  the  need  for  guidance. 

This  volume  is  in  no  sense  a  compilation.  For  the 
most  part  it  reflects  personal  experiences  gained  during 
ten  years  of  intimate  contact  with  hog  cholera  in  the 
capacity  of  practicing  and  consulting  veterinarian,  anti- 
hog-cholera  serum  producer  and  research  worker,  but 
acknowledgment  is  due  many  other  members  of  the 
veterinary  profession  whose  researches  and  observations 
have  revealed  many  of  the  foundation  facts  on  which  the 
subject  matter  rests.  For  statistical  and  other  data  I 
have  consulted  other  authors  freely,  relying  for  sta- 
tistics especially  on  the  numerous  and  excellent  publi- 
cations of  the  United  States  Bureau  of  Animal  Industry. 
I  am  indebted  to  Dr.  E.  A.  Cahill,  Director  of  the  Pit- 
man-Moore Biological  Laboratories,  Zionsville,  Indiana, 
for  some  of  the  illustrations. 

Dr.  V.  A.  Moore,  Dean  of  the  New  York  State  Veteri- 
nary College  at  Cornell  University,  and  Dr.  J.  W.  Benner 
of  the  College  Experiment  Station  Staff  have  read  the 
manuscript,  and  each  has  offered  many  valuable  sug- 
gestions which  are  deeply  appreciated. 

Great  care  has  been  taken  to  make  the  book  a  conserva- 
tive and  accurate  guide  for  the  practicing  veterinarian 
who  must  accept  farm  conditions  as  he  finds  them  and 
handle  hog  cholera  so  as  to  secure  and  retain  the  con- 
fidence of  his  clients.  If  among  other  imperfections 
there  are  departures  from  this  ideal  I  trust  that  my 
readers  will  direct  my  attention  to  them. 

R.  R.  B. 


CONTENTS 

CHAPTER 

I    HISTORY  AND  ECONOMIC  IMPORTANCE  .     .     ,     .  1 

II    NATURE  AND  CAUSE  OF  HOG  CHOLERA  ....  7 

III  METHODS  OF  DISSEMINATION 17 

IV  COMPLICATIONS 21 

V    SYMPTOMS  AND  LESIONS 35 

VI    DIAGNOSIS,  DIFFERENTIAL  DIAGNOSIS,  PROGNOSIS  58 

VII    PREPARATION  OF  ANTI-HOG-CHOLERA  SERUM  AND 

HOG  CHOLERA  VIRUS 76 

VIII    METHODS  OF  USING  ANTI-HOG-CHOLERA  SERUM  .  118 

IX    HANDLING  HOG  CHOLERA  IN  THE  FIELD  .     .     .  158 

X    HOG  CHOLERA,  MEAT  INSPECTION  AND  GARBAGE 

FEEDING 197 

XI    CONTROL  AND  ERADICATION  OF  HOG  CHOLERA  230 


ILLUSTRATIONS 

PAGE 

1.  Shoats  affected  with  acute  hog  cholera 37 

2.  Lung  of  pig  showing  ecchymoses  due  to  acute  hog 

cholera 46 

3.  Left  auricle  of  pig's  heart  showing  petechise  due  to 

acute  hog  cholera 48 

4.  Spleens  showing  hemorrhages  which  are  rather  typ- 

ical of  acute  hog  cholera 49 

5.  Kidney  of  pig  showing  numerous  petechiae  due  to 

acute  hog  cholera 51 

6.  Lymph  glands  of  pig  showing  hemorrhages  caused 

by  acute  hog  cholera 54 

7.  Bleeding  room  in  anti-hog-cholera  serum  laboratory. 

(Courtesy  Pitman-Moore  Biological  Laboratories)       77 

8.  Corner  of  anti-hog-cholera  serum  laboratory.     New 

York   State  Veterinary   College   at   Cornell  Uni- 
versity       79 

9.  Post-mortem  room  where  autopsies  on  virus  pigs 

are  held 88 

10.  A  close  view  showing  the  hypering  process    ...  91 

11.  Bleeding  unit,  and  hog  prepared  for  bleeding    .     .  99 

12.  Bleeding  for  serum  .      .      .     .     .     .    -.     .     .      .  101 

13. J  Testing  anti-hog-cholera  serum 107 

14.    Injecting  anti-hog-cholera  serum  in  the  ham  .     .     .  119 

ix 


ILLUSTRATIONS 


15.  Method   of  holding  shoat   for  injecting   serum   in 

axillary  space 120 

16.  An  improvised  method  of  holding  shoats  for  immun- 

izing  121 

17.  Convenient  hog  holder  made  from  %  inch  gas  pipe, 

and  flexible  clothes  wire 123 

18.  Method  of  preparing  snout  rope  for  confining  large 

hogs 124 

19.  Method  of  noosing  the  snout  of  hog 125 

20.  Injecting  serum  behind  the  ear 129 


HOG  CHOLERA 

CHAPTER  I 

HISTORY  AND  ECONOMIC  IMPORTANCE 

HOG  cholera  seems  to  have  appeared  first  on 
American  soil  in  1833,  at  which  time  an  outbreak 
of  the  disease  was  reported  in  the  Ohio  valley. 
It  is  not  definitely  known  whether  the  malady  orig- 
inated in  this  country  or  in  Europe,  but  it  is 
a  rather  significant  fact  that  the  wild  hog  has 
flourished  in  Eurasia,  and  not  in  North  America, 
in  spite  of  the  fact  that  the  fauna  of  the  two 
continents  are  in  most  other  respects  very  closely 
related.  It  is  also  of  special  significance  that  the 
earliest  authentic  report  we  have  of  the  disease 
in  this  country  was  made  at  a  time  when  railroads 
were  first  being  put  into  operation.  It  is  there- 
fore possible  that  it  really  existed  in  America 
prior  to  that  time,  and  that  lack  of  facilities  for 
its  rapid  spread  prevented  it  from  assuming  the 
proportions  of  an  epizootic. 

It  is  true  that  as  early  as  1822  an  epizootic  dis- 
ease resembling  hog  cholera  was  reported  in 


2.  ;         ,  <  HOG    CHOLERA 

France,  and  there  is  evidence  that  prior  to  1833 
outbreaks  of  a  similar  nature  occurred  in  other 
parts  of  continental  Europe.  But  even  with  pres- 
ent-day knowledge  hog  cholera  and  other  infec- 
tious swine  diseases  are  sometimes  difficult  to 
differentiate,  and  we  are  thus  in  the  dark  relative 
to  the  true  causes  of  all  the  earlier  outbreaks. 

According  to  the  most  authentic  records,  hog 
cholera  appeared  in  England  in  1862,  and  from 
there,  in  1887,  it  was  carried  to  Sweden  in  a  ship- 
ment of  boars.  In  this  same  year  the  disease  ap- 
peared in  France  and  Denmark,  and  its  spread 
was  so  rapid  and  persistent  that  all  European 
countries  have  suffered  severely  from  its  ravages. 
To-day,  no  large  area  devoted  extensively  to  swine 
raising  is  entirely  free  from  hog  cholera,  and  so 
far  as  we  have  been  able  to  ascertain,  no  country, 
once  invaded,  has  succeeded  in  freeing  itself  of 
the  malady.  The  Scandinavian  countries  seem  to 
have  suffered  least  from  its  effects. 

Because  of  its  rapid  spread  and  high  mor- 
tality hog  cholera  has  caused  and  is  causing  enor- 
mous losses,  the  estimate  being  that  in  the  United 
States  it  is  responsible  for  ninety  per  cent  of  the 
deaths  from  all  swine  diseases.  In  this  country 
the  annual  losses  caused  by  it  during  the  last  four 
decades  have  ranged  between  $13,000,000  and 
$200,000,000,  and  in  the  two  decades  ending  with 
the  year  1914  the  average  annual  loss  per  one 


HISTORY   AND   ECONOMIC   IMPORTANCE  6 

thousand  hogs  has  been  approximately  66.  In 
1897,  the  loss  per  thousand  ran  as  high  as  130. 
Since  1914,  the  losses  due  to  the  disease  have  been 
gradually  diminishing,  and  it  is  believed  that  more 
effective  sanitary  measures  and  more  extensive 
and  judicious  use  of  protective  serum  have  been 
responsible  for  this  decline. 

Naturally  a  disease  of  such  great  economic  im- 
portance has  been  the  object  of  close  and  pro- 
longed study.  In  1875,  Dr.  James  Law  furnished 
the  United  States  Department  of  Agriculture  with 
a  report  setting  forth  accurately  the  symptoms 
and  lesions  of  the  disease,  and  speaking  for  its 
transmissibility.  Three  years  later,  as  a  member 
of  a  commission  of  nine  men  appointed  by  the  De- 
partment to  investigate  the  disease,  he  succeeded 
in  transmitting  it  by  inoculation  experiments.  Dr. 
Detmers,  acting  as  a  member  of  the  same  commis- 
sion, isolated  an  organism  which  he  regarded  as 
its  cause,  but  his  findings  were  not  confirmed. 

In  1885,  Dr.  Daniel  Elmer  Salmon  and  Dr.  Theo- 
bald Smith  isolated  an  organism,  now  known  as  B. 
suipestifer,  which  they  believed  to  be  the  true 
cause  of  hog  cholera.  Their  work  was  confirmed 
by  trained  investigators  in  this  country  and  Eu- 
rope, but  all  attempts  to  produce  immunity  to 
field  outbreaks  by  using  B.  suipestifer  as  an  im- 
munizing agent  ended  in  failure.  Thus  during 
the  late  nineties  considerable  doubt  had  developed 


4  HOG    CHOLERA 

among  some  scientists  relative  to  the  true  signifi- 
cance of  this  organism  in  its  relation  to  epizootic 
hog  cholera.  This  doubt  was  aroused  because 
hogs  that  sickened  as  a  result  of  injections  of  B. 
suipestifer  cultures  failed  to  transmit  disease  to 
checks,  because  those  that  survived  injection  with 
cultures  of  the  organism  were  not  immune  when 
exposed  in  field  outbreaks,  and  because  these  cul- 
tures did  not  always  produce  disease,  while  blood 
from  hogs  sick  as  a  result  of  natural  infection 
proved  to  be  quite  generally  infectious.  In  1903, 
de  Schweinitz  and  Dorset  of  the  United  States 
Bureau  of  Animal  Industry  demonstrated  that  the 
true  cause  of  epizootic  hog  cholera  is  a  filterable 
virus,  and  this  marked  an  epoch  in  th6  history  of 
the  disease. 

Proceeding  in  the  light  of  this  new  knowledge, 
Dorset,  Niles  and  McBryde  succeeded,  in  1908,  in 
adapting  to  hog  cholera  the  principles  employed 
by  Kolle  and  Turner,  Nicolle  and  Adil-Bey  in  pro- 
ducing a  protective  serum  against  rinderpest,  a 
disease  of  cattle  caused  by  a  filterable  virus. 
The  work  of  Dorset  and  his  associates  was  con- 
firmed by  numerous  investigators,  among  whom 
were  Uhlenhuth,  Hutyra  and  Xylander,  and  the 
epochal  field  experiments  conducted  in  this  coun- 
try by  Dr.  Niles  and  described  by  him  in  the  re- 
port of  the  United  States  Bureau  of  Animal  In- 
dustry, 1908,  fully  established  the  great  practical 


HISTORY   AND   ECONOMIC    IMPORTANCE  O 

usefulness  of  anti-hog-cholera  serum  in  checking 
the  inroads  of  hog  cholera  in  the  field. 

Since  1908,  rapid  advances  have  been  made  in 
providing  for  an  adequate  supply  of  serum,  in 
refining  it,  in  working  out  methods  for  its  use  in 
the  field,  and  in  regulating  its  production  so  as  to 
prevent  sale  of  that  which  is  contaminated  or  im- 
potent. All  important  hog-raising  states  in  the 
Union  have  made  provision  to  manufacture  serum, 
and  scores  of  private  laboratories  which  have 
been  established  are  being  operated  under  super- 
vision of  the  Bureau  of  Animal  Industry.  In  the 
refinement  of  the  serum  the  aim  has  been  to  pro- 
duce, at  low  cost,  a  clear,  sterile,  potent  product 
with  good  keeping  qualities.  This  ideal  is  rapidly 
being  attained,  but  there  are  still  serious  questions 
regarding  uniform  potency  and  keeping  qualities 
of  the  clear  serum,  and  the  equipment  required  in 
making  it  is  rather  crude,  and  cannot  be  said  to 
have  passed  the  developmental  stage. 

Finally,  it  should  be  related  that  with  the 
knowledge  that  hog  cholera  can  be  controlled, 
there  has  appeared  a  quickened  interest  in  all 
other  maladies  that  affect  swine,  especially  those 
frequently  complicated  with  hog  cholera.  Undue 
importance  has  sometimes  been  attached  to  some 
of  these  diseases,  and  such  extravagant  claims 
have  been  made  for  certain  biologies  used  as  pro- 
phylactic or  therapeutic  agents  that  there  has 


6  HOG   CHOLEKA 

been  a  sharp  reaction,  and  there  are  indications 
at  present  that  the  trend  of  opinion  may  even 
swing  too  far  in  the  opposite  direction.  The  dis- 
eases that  complicate  hog  cholera  present  very 
real  problems,  and  experimental  work  looking  to- 
ward a  deeper  understanding  of  them  is  one  of  the 
immediate  needs  of  the  present  day. 


CHAPTER  II 

NATURE  AND  CAUSE  OF  HOG  CHOLEBA 

HOG  cholera  is  an  acute,  communicable,  febrile 
disease  which  attacks  swine  of  all  breeds  and  ages, 
but  does  not  affect  other  domesticated  animals,  or 
man.  It  is  a  septicemia.  Occasionally  a  per- 
acute  form  of  the  disease  is  recognized  during  the 
first  days  of  an  outbreak  and  chronic  hog  cholera 
is  frequently  observed  among  the  stragglers  that 
survive  the  more  severe  and  rapidly  terminating 
forms.  In  the  individual,  the  disease  is  charac- 
terized by  sudden  onset,  inappetence,  chilling^ 
very  high  fever,  arched  back,  a  disposition  to  hide 
in  the  litter,  constipation  followed  by  diarrhea, 
general  weakness  in  the  later  stages,  accompanied 
by  purplish  discolorations  of  the  skin  covering  the 
belly,  ears  and  snout.  In  the  herd,  the  onset  is 
relatively  slow,  the  first  death  usually  preceding 
subsequent  ones  several  days,  but  after  the  first 
week  the  outbreak  rapidly  gains  momentum,  and 
in  a  comparatively  short  time  all  hogs  become  in- 
fected. The  mortality  ranges  between  80  and  100 
per  cent  with  a  strong  tendency  to  approach  the 
latter  figure. 


8  HOG    CHOLEBA 

Young  pigs,  especially  those  farrowed  and 
nursed  by  immune  mothers,  are  often  immune  to 
cholera  during  the  first  few  weeks  of  life,  and  a 
general  impression  that  all  pigs  nursing  immune 
sows  are  likewise  immune  seems  to  have  gained 
ground.  This  impression  is  not  in  accord  with 
the  facts,  for  we  have  seen  individual  pigs  born  of 
immune  mothers  and  suckled  by  them,  dead  of 
hog  cholera  on  the  seventh  day  following  birth, 
and  under  like  conditions  of  birth  and  sustenance 
we  have  frequently  seen  entire  litters  succumb  to 
the  disease  before  attaining  an  age  of  four  weeks. 
Among  older  hogs  raised  in  localities  where  hog 
cholera  is  not  prevalent,  the  "  natural  immunes" 
so  frequently  mentioned  are  by  no  means  common, 
and  it  is  probable  that  in  places  where  they  are 
found  in  considerable  numbers  they  owe  their  im- 
munity to  the  fact  that  they  are  exposed  to  cholera 
as  young  pigs,  and  suffering  only  a  slight  reac- 
tion, are  rendered  immune.  As  a  general  rule, 
young  shoats,  old  hogs,  and  sucking  pigs  are  most 
susceptible  to  cholera  in  the  order  named,  and,  as 
would  be  expected,  recoveries  from  the  disease 
are  less  frequent  among  young  shoats,  and  more 
frequent  among  old  sows  and  sucking  pigs. 

The  cause  of  hog  cholera  is  a  filterable  virus, 
probably  an  organism  too  small  to  be  visible  with 
the  highest  magnification  now  obtainable,  and  pos- 
sibly possessed  of  characteristics  which  prevent  it 


STATUBE    AND    CAUSE    OF    HOG    CHOLEEA 

from  taking  stains  that  render  bacteria  more 
plainly  visible.  The  virus  readily  passes  porce- 
lain and  infusorial  earth  filters  which  retain  all 
visible  bacteria,  but  it  is  itself  retained  by  the 
finest  porcelain  filters.  It  does  not  pass  through 
colloid  membranes.  In  the  human  subject,  mea- 
sles, mumps,  scarlet  fever  and  smallpox  are  among 
the  diseases  caused  by  filterable  viruses,  while 
among  animals  rinderpest,  foot-and-mouth  dis- 
ease and  rabies  are  some  of  the  diseases  that  fall 
in  the  same  group.  The  classification  is  a  rather 
loose  one,  being  based  entirely  on  the  fact  that 
these  viruses  will  pass  filters  that  retain  visible 
bacteria,  rather  than  on  morphological  or  cultural 
characteristics. 

There  is  no  conclusive  evidence  that  hog  cholera 
virus  has  been  propagated  outside  the  bodies  of 
infected  swine.  After  a  hog  has  been  exposed  to 
the  disease  and  actually  infected,  the  virus  ap- 
pears in  the  blood  stream  in  about  four  days,  and 
thus  all  vascular  organs  harbor  it  during  the  at- 
tack. In  the  later  stages  of  a  few  chronic  cases, 
we  have  found  the  blood  free  of  the  virus,  but  we 
do  not  know  whether  this  is  the  rule,  nor  is  there 
definite  knowledge  of  the  part  played  by  "  car- 
riers "  in  harboring  it.  It  is  eliminated  through 
the  excretions.  The  urine  is  regularly  infectious, 
the  feces  may  or  may  not  contain  it,  and  the  dis- 
charge from  the  eyes  and  skin  ulcers  is  infectious 


10  HOG   CHOLERA 

at  least  in  some  instances.  Just  how  any  one  of 
the  filterable  viruses  operates  to  produce  disease 
is  quite  unknown,  but  it  is  certain  that  hog  cholera 
virus  has  a  selective  action  for  epithelial  and  en- 
dothelial  cells. 

Virulence.  Hog  cholera  virus  produces  speci- 
fic disease  only  in  swine,  and  very  small  quantities 
of  infected  material  are  sufficient  to  cause  death 
in  susceptible  animals.  According  to  King,  sub- 
cutaneous injections  of  1/86  of  a  mil  of  virulent 
blood  produced  the  disease,  while  lesser  amounts 
produced  only  a  mild  reaction,  or  none  at  all. 
Natural  infection  usually  occurs  by  way  of  the 
digestive  system,  but  the  disease  is  readily  pro- 
duced by  subcutaneous,  intravenous  or  intra-abdo- 
minal  injections  of  small  quantities  of  virulent 
material. 

Resistance.  Most  of  the  natural  influences  to 
which  hog  cholera  virus  is  subjected  do  not  oper- 
ate to  destroy  it  rapidly.  Drying,  sunlight,  and 
low  temperatures  seem  to  have  no  immediate  at- 
tenuating effects,  although  it  is  a  fact  that  most 
infected  yards  which  remain  uninhabited  from 
three  to  six  months  do  not  endanger  susceptible 
pigs  placed  in  them.  There  is,  though,  a  consid- 
erable tendency  for  hog  cholera  to  recur  on  old 
infected  farms,  and  this  fact  indicates  that  there 
are  exceptional  cases  in  which  the  span  of  life 
of  the  virus  is  greatly  prolonged. 


NATURE   AND    CAUSE    OF   HOG    CHOLERA  11 

Putrefaction  is  the  only  natural  influence 
which  operates  to  destroy  the  virus  rapidly.  Ac- 
cording to  Uhlenhuth  it  will  live  in  putrefying  car- 
casses for  about  eight  days,  but  undoubtedly  the 
many  influences  which  govern  putrefactive  proc- 
esses render  data  of  this  kind  of  value  merely  in 
establishing  tendencies.  It  is  certain  that  decom- 
posing carcasses  do  not  harbor  the  virus  regu- 
larly, and  likewise  it  is  true  that  virus  kept  in  bot- 
tles in  the  laboratory  often  is  killed  when  putre- 
faction develops.  When  sufficient  preservative  is 
added  to  prevent  the  growth  of  putrefactive  or- 
ganisms, the  virus  regularly  lives  several  months, 
and  may  even  exist  for  years. 

Moderate  degrees  of  heat  attenuate  or  destroy 
the  virus,  and  under  no  circumstances  has  it  been 
found  to  survive  temperatures  near  the  boiling 
point.  The  following  rather  incomplete  table  pre- 
pared by  the  German  Imperial  Board  of  Health 
laboratories  gives  a  fair  idea  of  the  effects  pro- 
duced by  various  degrees  of  heat. 


Degrees 

Material       Centigrade  Time  Results 

Liquid  serum 
filtrate  45  24  hours  Not  killed  or 

weakened 
Liquid  serum 
filtrate  46.5  24  hours  Not  killed  or 

weakened 


12 


HOG   CHOLEEA 


Degrees 

Material       Centigrade 
Liquid  serum 
filtrate  46 

Liquid  serum 
filtrate  55 

Liquid  serum 
filtrate  60 

Liquid  serum 
filtrate  58 

Liquid  serum 
filtrate 
Dried  blood 
Dried  blood 
Dried  blood 


Urine 
Urine 


78 
65 

72 
72 
58 
58 


Time 

Results 

48  hours 

Killed 

24  hours 

Killed 

10  hours 

Killed 

2  hours 

Not  killed 

1  hour 
2  hours 
1  hour 
!/2  hour 
1  hour 
%  hour 

Killed 
Not  killed 
Killed 
Killed 
Killed 
Not  killed 

Low  temperatures  act  to  prevent  growth  of 
putrefactive  organisms  and  are  thus  instrumental 
in  prolonging  the  life  of  the  virus.  In  our  own 
experiments,  hams  removed  from  cholera  infected 
pigs  and  frozen  hard  ninety-three  days  still  har- 
bored virus  sufficient  to  produce  the  disease  when 
small  portions  of  them  were  fed  to  susceptible 
pigs. 

Disinfectants.  Hog  cholera  virus  readily  re- 
sists ordinary  disinfectants  in  dilutions  that  are 
rapidly  fatal  to  most  bacteria.  When  y2  per  cent 
phenol  is  added  to  virulent  blood,  the  virus  will 
remain  alive  for  months,  and  all  of  the  coal  tar 
disinfectants  must  be  prepared  in  strong  solutions 
in  order  to  destroy  it.  Liquor  cresolis  compositus 


NATURE   AND    CAUSE    OF    HOG    CHOLERA 


13 


in  5  per  cent  aqueous  solution,  when  allowed  to  act 
for  an  hour  or  more,  has  proved  effective  in  killing 
it.  Following  is  a  table  prepared  by  the  German 
Imperial  Board  of  Health  laboratories,  which  fur- 
nishes additional  information  relative  to  the  effec- 
tiveness of  various  disinfectants  when  used  to  kill 
hog  cholera  virus.  Most  of  the  tests  were  made 
by  mixing  10  mils  of  the  virus  with  an  equal 
quantity  of  aqueous  dilution  of  the  disinfectant. 

Dilution 
applied 


Disinfectant 

Corrosive 

sublimate 

Corrosive 
sublimate 

Corrosive 
sublimate 


Carbolic 
acid 

Carbolic 
acid 

Carbolic 
acid 

Carbolic 
acid 


0.3  per  cent  solution 


0.5  per  cent  solution 


Result 

Serum    filtrate    not 
killed  in  8  days. 

Serum  filtrate  virus 
not  killed  in  4  days. 


0.2  per  cent  solution  Urine  virus  killed 
in  15  minutes  in 
one  trial.  In  another 
trial  not  killed. 

0.5  per  cent  solution  Serum  filtrate  virus 
not  killed  in  8  days. 

1.0  per  cent  solution  Serum  filtrate  virus 
not  killed  in  4  days. 

3.0  per  cent  solution  Failed  to  kill  blood 
virus  in  8  days. 

2.5  per  cent  solution  Failed  to  kill  urine 
virus  in  15  minutes. 


14 


HOG    CHOLEBA 


Dilution 

Disinfectant  applied 

Chloroform        Full  strength 


Sodium 

taurocholate 

Formaldehyd    2.5  per  cent  solution 


Lugol  's 

solution  0.25  per  cent  solution 


Urea 


20.0  per  cent  solution 


Glycerin          33.0  per  cent  solution 


Ozone 


Hydrogen 

peroxid  10.0  per  cent  solution 

Antiformin  5.0  per  cent  solution 

Antiformin  2.0  per  cent  solution 


Result 

Serum  filtrate  virus 
not  killed  in  24 
hours. 

Blood      virus      not 
killed  in  4  days. 
Serum  filtrate  virus 
alive  after  one  hour. 
Dead  in  15  days. 

Failed  to  kill  serum 

filtrate    virus    in    2 

hours. 

Did  not  kill  serum 

filtrate    virus   in    1 

month. 

Failed  to  kill  serum 

filtrate    virus    in    1 

month. 

Blood      virus      not 

killed. 

Serum  virus  not 
killed  in  two  hours. 
Serum  filtrate  virus 
killed  in  one  hour. 
Urine  virus  not 
killed  in  10  minutes. 
Killed  in  15  min- 
utes. 


Antiformin       1.0  per  cent  solution  Serum  filtrate  virus 

not     killed     in     24 
hours. 


NATURE   AND    CAUSE    OF    HOG   CHOLERA 


15 


Disinfectant 
Antiformin 


Milk  of  lime 


Chlorid 
of  lime 

Lysol 


Dilution 

applied  Result 

2.5  per  cent  solution  Serum  filtrate  virus 
killed  in  2  hours. 
Blood  virus  not 
killed  in  two  hours. 

Failed  to  kill  in  one 

hour.  In  other  ex- 
periments killed  in 
20  min. 

5.0  per  cent  solution  Serum  virus  killed 
in  1%  hours. 

3.0  per  cent  solution  Serum  filtrate  virus 
usually  killed  in  1 
hour. 


Cresol  soap 

solution          3 — 6  per  cent  solution  Always  killed  virus 

in  1  hour. 
Cresol  soap 
solution          3 — 4:  per  cent  solution   Serum  filtrate  virus 

not     killed     in     % 

hour. 

Cresol  soap 
solution  3.0  per  cent  solution  Killed    urine    virus 

in  y^  hour. 

Since  a  filterable  virus  has  been  incriminated  as 
the  true  cause  of  hog  cholera,  various  investiga- 
tors have  from  time  to  time  attempted  to  isolate  it, 
stain  it,  and  grow  it  on  artificial  culture  media. 
King  has  made  an  exceedingly  careful  study  of  a 
spirochaete  (Spirochaeta  hyos)  which  to  him  has 
seemed  to  possess  etiological  significance,  but  his 


16  HOG   CHOLEEA 

work  has  never  been  verified.  More  recently 
Proescher  and  Sell  have  described  a  diplococcus 
which  they  are  inclined  to  regard  as  the  virus  of 
hog  cholera,  but  as  yet  they  have  not  submitted 
substantial  proof  to  justify  such  a  claim.  Certain 
cell  inclusions  which  in  cholera-infected  hogs  ap- 
pear in  the  epithelial  cells  of  the  conjunctival  sac 
have  also  been  regarded  as  possible  possessors  of 
pathogenic  powers,  but  it  now  seems  probable  that 
these  exist  as  an  effect  rather  than  as  a  cause. 
There  are  various  organisms  which,  acting  as 
secondary  invaders,  exert  profound  influence  on 
the  course  of  hog  cholera  and  on  the  lesions  which 
develop,  but  which  should  in  no  way  be  confused 
with  the  filterable  virus  that  produces  the  dis- 
ease. These  will  be  considered  in  another  chap- 
ter. 


CHAPTER  III 

METHODS  OF  DISSEMINATION 

HOG  cholera  virus  exists  only  in  infected  hogs 
and  in  material  contaminated  by  their  excretions, 
and  this  is  the  fundamental  fact  to  which  we  must 
repeatedly  refer  in  accounting  for  new  outbreaks. 
There  are  numerous  exceptions  to  the  rule,  but 
the  individual  outbreak  can  usually  be  traced  to 
a  definite  source,  and  this  fact  is  important  in  its 
relation  to  measures  for  control. 

Shipping  infected  animals  is  probably  the  one 
practice  responsible  for  most  new  herd  infections. 
It  is  not  uncommon  for  a  breeder  to  become  dis- 
couraged when  his  hogs  begin  to  die  and  to  ship 
all  seemingly  well  animals  to  a  distant  market. 
During  the  fall  of  the  year  especially  one  has  but 
to  stand  for  a  few  hours  at  the  unloading  chutes 
of  some  of  our  large  stockyards  in  order  to  realize 
how  nearly  universal  this  practice  has  become. 
Thus  most  public  stockyards  harbor  hog  cholera 
virus,  and  all  hogs  unloaded  in  them  and  later 
taken  to  farms  for  feeding  or  breeding  become 
potential  sources  of  danger. 

In  the  eastern  states  garbage  feeding  is  re- 
sponsible for  more  outbreaks  of  hog  cholera  than 

17 


18  HOG    CHOLERA 

all  other  factors  combined,  and  in  the  country 
as  a  whole  this  practice  plays  an  exceedingly  im- 
portant part  in  the  spread  of  the  virus  from  local- 
ity to  locality.  Many  hogs  are  killed  while  they 
are  in  the  incubation  period  of  cholera,  and  pork 
that  comes  from  their  carcasses,  even  though  it  is 
fit  for  human  food,  will  produce  hog  cholera  when 
fed  in  small  portions  to  hogs.  Bits  of  this  in- 
fected pork  find  their  way  into  garbage  which  is 
fed  to  susceptible  swine,  and  the  cycle  is  com- 
plete. 

The  use  of  hog  cholera  virus  in  the  field  in 
serum-virus  immunization  has  now  become  a  rou- 
tine measure,  and  despite  the  advantages  that  re- 
sult from  this  practice,  it  must  in  truth  be  said 
that  it  is  responsible  for  many  new  outbreaks  of 
hog  cholera.  The  practice  of  giving  feeding 
shoats  serum-virus  treatment  and  shipping  them 
immediately  to  distant  points  operates  to  infect 
much  new  territory,  and  is  often  the  cause  of 
heavy  losses  among  the  hogs  thus  handled. 
"Vaccination  cholera,"  as  these  " breaks "  follow- 
ing serum-virus  treatment  are  called,  although  it 
usually  runs  a  less  rapid  course  which  invites  sec- 
ondary infection,  is  not  fundamentally  different 
from  hog  cholera  contracted  as  a  result  of  natural 
infection,  but  there  is  a  marked  tendency  in  some 
quarters  to  avoid  the  issue  and  attribute  the 
deaths  to  causes  other  than  hog  cholera  virus. 


METHODS    OF   DISSEMINATION  19 

The  practice  of  taking  breeding  hogs  to  dis- 
tant points  to  mate  them  is  a  fruitful  source  of 
new  herd  infections,  and  in  more  than  one  instance 
we  have  known  the  virus  to  be  carried  from  one 
farm  to  another  as  a  result  of  neighbors  exchang- 
ing help  during  butchering  time.  Small  streams 
to  which  many  hogs  have  access  may  also  become 
polluted  and  carry  destruction  to  herds  below  the 
one  in  which  the  original  infection  occurs.  Show 
hogs  returned  from  fairs  often  contract  hog  chol- 
era en  route  or  during  their  contact  with  other 
hogs  in  the  show  ring,  only  to  infect  the  herds  they 
represent  when  they  return  home. 

Besides  the  regular  channels  of  infection  which 
we  have  already  indicated,  and  which  severally 
are  responsible  for  most  new  outbreaks  of  hog 
cholera,  there  are  almost  an  infinite  number  of 
casual  carriers  of  the  virus,  such  as  crows,  spar- 
rows, buzzards,  pigeons,  and  various  predatory 
animals.  These,  by  feeding  in  infected  yards  or 
on  carcasses  of  hogs  dead  of  cholera,  may  carry 
the  infection  to  clean  territory,  but  the  probabili- 
ties are  that  in  most  localities  the  number  of  herds 
thus  infected  is  relatively  small. 

In  recent  experiments  Dr.  Marion  Dorset  has 
found  it  difficult  to  transmit  hog  cholera  from 
herd  to  herd  by  employing  attendants,  pigeons 
and  sparrows  as  agents  of  transmission,  and  in 
our  own  experiments  we  have  failed  in  a  surpris- 


20  HOG    CHOLEEA 

ing  percentage  of  cases  to  infect  yards  with  hogs 
sick  of  cholera  so  that  susceptibles  placed  in  them 
subsequently  will  contract  the  disease.  In  spite 
of  these  facts,  though,  we  must  in  handling  hog 
cholera  be  guided  by  the  practically  universal 
clinical  experience  which  teaches  that  when  hog 
cholera  once  finds  its  way  into  a  farm  herd  it  will 
eventually  infect  all  individuals  in  it,  irrespective 
of  the  fact  that  the  herd  may  consist  of  several 
pens  of  hogs  kept  some  distance  apart. 

It  is  impossible,  and  indeed  unnecessary,  to  dis- 
cuss in  detail  the  various  influences  which  occa- 
sionally are  instrumental  in  carrying  hog  cholera 
virus  from  herd  to  herd,  and  likewise  it  is  impos- 
sible to  assign  to  each  influence  a  relative  import- 
ance. It  is  much  more  important,  in  concluding 
this  chapter,  to  call  attention  again  to  the  fact 
that  in  the  great  majority  of  cases  hog  cholera 
virus  travels  in  certain  quite  definite  channels,  and 
that  new  outbreaks  are  usually  the  direct  or  in- 
direct result  of  shipping  or  moving  infected  hogs, 
or  else  they  originate  from  the  practice  of  garbage 
feeding,  or  that  of  using  hog  cholera  virus  indis- 
criminately in  seeking  to  immunize  against  the 
disease. 


CHAPTER  IV 

COMPLICATIONS 

BEFORE  we  consider  the  symptoms,  lesions  and 
diagnosis  of  hog  cholera,  it  is  necessary  that  we 
shall  discuss  briefly  some  of  the  organisms  that 
complicate  the  disease,  and  which  at  times  exert 
such  profound  influence  on  its  course  that  autop- 
sies become  a  continual  source  of  surprise  and 
perplexity  to  the  diagnostician.  No  attempt  will 
be  made  to  give  complete  morphological  and  cul- 
tural characteristics  of  these  organisms,  which  in- 
formation may  be  found  in  various  standard 
works  on  bacteriology.  The  scope  and  purpose 
of  this  book  require  that  we  shall  deal  only  in  a 
general  way  with  most  biological  characteristics, 
confining  our  attention  chiefly  to  disease  produc- 
ing power,  especially  in  swine. 

Bact.  suisepticum  is  the  most  important  of  the 
organisms  that  complicate  hog  cholera.  It  was 
isolated  and  described  by  Loeffler  and  Schiitz  in 
1885,  and  in  1886  Dr.  Theobald  Smith  recovered 
it  from  various  organs  of  many  hogs  dead  of  an 
epizootic  disease  in  this  country.  Moore  showed 

that  it  is  present  in  the  upper  air  passages  of 

21 


22  HOG   CHOLEBA 

many  healthy  swine.  In  the  absence  of  knowledge 
of  the  filterable  hog  cholera  virus,  all  these  investi- 
gators were  inclined  to  regard  the  organism  as  the 
cause  of  epizootic  swine  plague,  and  to  ascribe 
repeated  failures  in  causing  it  to  produce  trans- 
missible disease,  to  the  fact  that  field  conditions 
could  not  be  duplicated  in  the  laboratory. 

The  organism  is  rod-shaped  varying  in  length 
from  .8  to  2  microns,  and  in  width  from  .4  to  1.2 
microns.  Often  the  ends  are  rounded  giving  it 
an  oval  shape,  but  it  is  not  uncommon  for  the  rods 
to  be  so  short  as  to  resemble  micrococci.  Some- 
times involution  forms  are  observed.  In  cover- 
glass  preparations  made  direct  from  the  tissues 
and  stained  with  basic  aniline  dyes,  Bact.  suisepti- 
cum  often  stains  heavily  at  the  ends  and  around 
the  periphery,  and  very  lightly  or  not  at  all  in  the 
center.  Preparations  made  from  cultures  do  not 
as  a  rule  exhibit  this  bipolar  staining. 

The  organism  is  subject  to  wide  variation  in 
virulence.  Babbits,  mice  and  guinea-pigs  readily 
succumb  to  injections  of  minute  quantities  of  cul- 
tures or  suspensions  containing  it.  Babbits  are 
especially  susceptible,  usually  dying  in  less  than 
thirty-six  hours  of  an  acute  bacteremia.  Like  cul- 
tures or  suspensions  injected  subcutaneously  into 
cholera  immune  pigs  produce  as  a  rule  a  transient 
local  reaction.  Small  doses  injected  intravenously 
may  or  may  not  prove  fatal,  but  large  intrave- 


COMPLICATIONS  23 

nous  doses  produce  death  from  septicemia  quite 
regularly.  The  pigs  that  die  in  less  than  seventy- 
two  hours  may  show  as  lesions  congestion  of  the 
lymph  glands  and  various  parenchymatous  or- 
gans, or,  more  rarely,  petechial  hemorrhages  in 
the  kidneys  and  heart,  indistinguishable  from 
those  observed  in  acute  hog  cholera.  In  the  cases 
in  which  the  disease  runs  a  less  rapid  course,  there 
is  a  rather  constant  tendency  for  joint  lesions  of 
an  inflammatory  nature  to  form,  and,  contrary  to 
what  might  be  expected,  pleuritis  and  pneumonia 
appear  much  less  frequently  than  these  joint  le- 
sions. Rarely  do  checks  kept  with  these  experi- 
mental animals  contract  disease.1 

The  symptoms  that  appear  in  pigs  artificially 
infected  with  large  intravenous  doses  of  Bact. 
suisepticum  are  observed  in  a  very  few  hours 
after  the  injection.  There  is  rapid  breathing, 
sometimes  an  extreme  degree  of  dyspnea,  or  the 
respiratory  disturbance  may  manifest  itself  in 
1 '  thumping. ' '  The  appetite  is  suspended,  the  tem- 
perature is  moderately  high  (104°-105.5°  F.)  and 
there  is  an  anxious  facial  expression.  A  general 
stiffness  is  practically  always  observed,  and 

*In  our  own  experiments,  in  which  more  than  100  pigs  were 
exposed  in  pens  with  pigs  artificially  infected  with  intravenous 
injections  of  Bact.  suisepticum,  3  contracted  disease  and  2  died. 
Bact.  suisepticum  was  recovered  from  the  blood  and  various 
parenchymatous  organs  of  the  dead  animals.  We  know  of  no 
other  well  authenticated  instances  in  which  like  transmission  has 
occurred. 


24  HOG    CHOLEEA 

lachrymation  often  is  pronounced.  If  death  or 
recovery  does  not  take  place  in  two  or  three  days, 
the  tendency  is  for  the  disease  to  assume  a  chronic 
type.  One  or  more  of  the  joints,  usually  the  knee 
or  hock,  becomes  hot,  painful,  and  swollen,  render- 
ing it  difficult  or  impossible  for  the  animal  to 
stand.  In  spite  of  this,  the  temperature  falls  and 
is  maintained  close  to  normal,  the  appetite  returns 
and  is  surprisingly  good  considering  the  condition 
of  the  animal  and  the  fact  that  progressive  ema- 
ciation is  taking  place.  Pneumonia  sometimes 
appears  in  these  chronic  cases,  adding  its  train  of 
symptoms,  but  it  fails  to  develop  in  a  surprising 
percentage  -of  cases,  thus  presenting  a  striking 
comparison  with  field  outbreaks  formerly  thought 
to  be  caused  solely  by  Bact.  suisepticum,  in 
which  pneumonia  is  the  most  constant  manifesta- 
tion. These  facts  lead  us  to  doubt  that  the  or- 
ganism, acting  alone,  is  the  cause  of  a  rapidly 
transmissible  disease  in  the  field. 

Field  observations  are  in  almost  perfect  accord 
with  these  experimental  data.  We  have  frequently 
had  outbreaks  of  "pure  swine  plague "  reported 
to  us,  and  in  those  we  have  investigated,  in  which 
there  was  evidence  of  transmissible  disease,  we 
have  without  exception  succeeded  in  positively 
demonstrating  or  establishing  the  probable  pres- 
ence of  the  filterable  hog  cholera  virus.  It  is  also 
significant  that  in  the  East,  at  least,  cholera  im- 


COMPLICATIONS  25 

mune  hogs  do  not  suffer  from  "  swine  plague "  if 
we  except  the  cases  in  which  it  is  said  to  appear 
in  the  first  month  subsequent  to  serum-virus  treat- 
ment, and  which  in  reality  have  their  origin  in 
the  hog  cholera  virus  used. 

Acting  as  a  secondary  invader  in  hogs  suffering 
with  cholera,  in  those  badly  infested  with  lung 
worms,  and  very  probably  as  a  primary  microbian 
cause  in  those  weakened  as  a  result  of  shipping, 
Bact.  suisepticum  regularly  produces  a  rather 
characteristic  bronchopneumonia,  and  hastens  or 
causes  death.  In  those  cases  in  which  it  acts  as  a 
secondary  invader  it  produces  pneumonia  so  rap- 
idly and  regularly  that  the  lesions  due  to  the  pri- 
mary cause  are  often  obscured  or  overlooked. 
Cholera  immune  farm  hogs  kept  in  exceedingly 
bad  sanitary  surroundings  and  exposed  regularly 
to  damp  and  inclement  weather,  have  not  been 
shown  to  suffer  from  a  rapidly  transmissible  and 
fatal  pneumonia  caused  by  this  organism.  There 
is,  though,  some  experimental  evidence  that  it  oc- 
casionally produces  pleuritis  or  possibly  slight 
pneumonic  lesions  from  which  most  hogs  recover. 

B.  suipestifer  (B.  cholera  suis)  is  another  or- 
ganism which  may  often  be  isolated  from  various 
parenchymatous  organs  of  hogs  dead  in  outbreaks 
of  cholera.  It  is  a  short,  motile  rod,  belonging 
to  the  colon  group.  In  1885  it  was  described  by 
Salmon  and  Smith  as  the  cause  of  epizootic  hog 


26  HOG   C^EOLEKA 

cholera.  In  later  years  Uhlenhuth  and  his  co- 
workers  reported  finding  it  in  the  intestinal  tracts 
of  many  healthy  swine.  Jordon,  in  this  country, 
was  unable  to  identify  it  in  any  normal  hogs  which 
he  examined,  and  neither  was  Tenbroeck.  Both 
of  these  investigators  regard  Uhlenhuth 's  work  as 
inconclusive  owing  to  the  fact  that  he  did  not 
differentiate  correctly  between  B.  suipestifer  and 
B.  paratyphoid  B.  Smith  states  that  the  only  dis- 
tinction that  can  be  made  between  the  two  is  that 
the  former  is  pathogenic  for  rabbits,  while  the 
latter  is  not. 

Eabbits  and  guinea-pigs  succumb  to  small  sub- 
cutaneous injections  of  cultures  of  B.  suipestifer, 
rabbits  being  somewhat  more  susceptible.  Swine 
are  not  easily  infected  with  subcutaneous  injec- 
tions, but  large  intravenous  doses  prove  fatal. 
According  to  Welch,  small  doses  may  lead  to  for- 
mation of  the  "button  ulcers"  observed  in  chronic 
hog  cholera,  and  Smith  secured  like  results  by 
feeding  pigs  bouillon  cultures. 

The  part  played  by  this  organism  in  producing 
swine  disease  in  the  field  is  not  well  defined,  as 
most  work  with  it  ceased  as  soon  as  the  filterable 
virus  was  accepted  as  the  cause  of  epizootic  hog 
cholera.  There  is  good  evidence  that  it  is  one 
cause  of  the  "button  ulcers "  just  mentioned,  and 
it  is  likewise  probable  that,  acting  in  the  role  of 
secondary  invader,  it  is  responsible  for  the  en- 


COMPLICATIONS  27 

larged,  dark,  and  somewhat  pulpy  spleens  ob- 
served in  individual  hogs  dead  in  outbreaks  of 
cholera.  It  also  seems  to  intensify  hemorrhagic 
lesions  produced  by  the  filterable  virus.  Its 
pathogenic  powers  in  relation  to  cholera  immune 
pigs  will  bear  further  investigation,  but  it  is  prob- 
able that  for  the  most  part  it  acts  to  complicate 
diseases  produced  by  other  causes. 

B.  pyocyaneus,  or,  according  to  Migula's  classi- 
fication, Pseudomonas  pyocyaneus,  is  a  motile  rod 
2  to  6  microns  long  and  .3  to  1  micron  broad.  It  is 
widely  distributed  in  nature,  and  there  has  been  a 
tendency  to  regard  it  chiefly  as  a  saprophyte.  It 
is  included  frequently  in  the  flora  of  wounds,  it 
appears  at  times  in  abscesses  in  swine  and  other 
animals,  and  it  has  been  described  as  the  cause  of 
an  outbreak  of  dysentery  in  man.  In  Germany  it 
is  said  to  be  the  cause  of  an  infectious  nasal 
catarrh  in  pigs,  and  we  have  found  it  associated 
with  outbreaks  of  pneumonia  in  swine,  as  the  prob- 
able cause. 

The  organism  is  an  aerobe,  it  grows  luxuriantly 
on  the  common  culture  media,  tending  to  over- 
whelm other  bacteria  associated  with  it.  It  has  a 
marked  tendency  to  produce  green  color  in  any  cul- 
ture medium,  and  the  sweetish  odor  produced  by 
it  in  bouillon  cultures  is  quite  characteristic.  It 
takes  the  aniline  stains  regularly,  and  is  Gram 
negative. 


28  HOG   CHOLERA 

B.  pyocyaneus  is  pathogenic  for  pigeons,  guinea 
pigs  and  rabbits.  In  swine,  it  is  not  regularly  so, 
but  under  certain  conditions  it  assumes  great 
pathogenic  significance.  We  have  failed  to  pro- 
duce disease  by  feeding  cultures  of  it  or  by  spray- 
ing them  into  the  nostrils  of  healthy  pigs,  while 
subcutaneous  doses  produced  nothing  more  than 
an  occasional  local  abscess.  Moderate  intrave- 
nous doses  of  suspensions  containing  it  cause 
dyspnea,  chilling  or  spasms  to  appear  immedi- 
ately, and  death,  preceded  by  paralysis,  usually  of 
the  hind  quarters,  often  takes  place  in  a  day  or 
two.  This  paralysis  is  observed  in  rabbits  as  well, 
and  must  be  regarded  as  a  more  or  less  constant 
but  nevertheless  specific  action  on  the  part  of  the 
organism.  According  to  Hutyra,  cultures  of  B. 
pyocyaneus  inoculated  directly  into  the  ethmoid 
mucosa  in  young  pigs,  produce  disease  similar  to 
the  catarrhal  rhinitis  observed  in  Germany. 

Under  natural  conditions  certain  predisposing 
factors,  among  which  early  age,  lung  worms,  hog 
cholera  virus  and  long  confinement  in  very  dusty 
quarters  are  most  important,  prepare  the  ground 
so  that  B.  pyocyaneus  exerts  its  pathogenic  pow- 
ers. We  have  observed  its  effects  following 
hyperimmunization  during  the  process  of  anti-hog- 
cholera  serum  preparation,  the  hypers  developing 
a  fatal  pneumonia  in  a  few  days  following  a  large 
intravenous  dose  of  hog  cholera  virus. 


COMPLICATIONS  29 

The  lesions  produced  in  swine  experimentally 
infected  by  means  of  intravenous  injections  of 
material  containing  B.  pyocyaneus  are  those  char- 
acteristic of  septicemia,  congestion  and  dark  col- 
oration of  the  lymph  glands,  lungs,  kidneys  and 
other  organs  appearing  regularly.  We  have  ob- 
served no  such  effects  where  natural  infection 
rules.  Here  the  constant  lesion  produced  is  pneu- 
monia, acute  or  chronic,  and  the  constant  symp- 
toms that  appear  are  those  that  may  be  referred 
to  this  condition. 

Dyspnea,  abdominal  breathing  and  other 
marked  evidence  of  respiratory  distress  charac- 
terize the  disease.  Paroxysms  of  coughing  occur 
when  the  hog  is  required  to  move,  the  alae  of  the 
nostrils  are  drawn  backward,  giving  the  snout  a 
peculiar  pointed  appearance,  and  it  is  not  uncom- 
mon for  the  affected  animals  to  assume  a  dog- 
sitting  position,  with  the  forelegs  placed  widely 
apart.  Thumping  appears  frequently.  Some- 
times there  is  a  yellowish  purulent  discharge  from 
the  nostrils.  The  appetite  may  or  may  not  be 
affected,  while  the  temperature,  as  a  rule,  remains 
normal  or  is  only  slightly  elevated. 

The  typical  lesion  which  we  have  found  associ- 
ated with  natural  infection  due  to  B.  pyocyaneus 
consists  of  a  semi-chronic  type  of  bronchopneu- 
monia,  affecting  first  the  ventral  and  cephalic 
portions  of  the  lungs,  or  if  lung  worms  are  pres- 


30  HOG    CHOLERA 

ent,  the  posterior  border  of  the  diaphragmatic  lobe 
as  well.  The  solidified  portions  may  be  red  but 
are  often  rather  light  in  color,  macroscopically 
resembling  the  surface  of  a  salivary  gland.  There 
is  a  marked  tendency  for  necrosis  to  develop 
from  numerous  foci,  and  multiple  abscesses  occur, 
appearing  as  slightly  elevated  yellow  areas  dotted 
over  the  surface  of  the  pneumonic  lung.  Pleuritis 
is  somewhat  constant,  and  a  high  degree  of  em- 
physema appears  in  the  dorsal  nonpneumonic  por- 
tion, giving  it  a  pale  white  color  as  compared  to 
the  normal  pink.  Often  there  is  distinct  evidence 
that  as  a  final  cause  of  death  an  acute  pneumonia 
is  superimposed  over  a  more  chronic  type,  in 
which  cases  all  parts  of  the  lungs  are  pneumonic, 
while  the  lesions  in  the  dorsal  and  posterior  por- 
tions are  of  more  recent  origin. 

B.  necrophorus  is  another  organism  that  some- 
times complicates  hog  cholera.  Although  subject 
to  wide  variations  in  form,  it  usually  appears  as  a 
long,  slender,  nonmotile  rod.  It  is  a  strict  anaer- 
obe, it  stains  with  the  ordinary  aniline  .dyes,  and 
is  Gram  negative.  Evidently  it  is  quite  widely 
distributed  in  nature,  for  it  appears  in  numerous 
necrotic  lesions  in  practically  all  domesticated  ani- 
mals. It  is  regarded  as  a  normal  inhabitant  of  the 
intestinal  tract  in  swine,  and  it  exists  in  soil  con- 
taminated with  manure.  It  is  the  exciting  cause 
of  calf  diphtheria,  lip  and  leg  ulceration  in  sheep, 


COMPLICATIONS  31 

and  a  necrotic  stomatitis  of  calves  and  pigs,  each 
of  which  partakes  somewhat  of  the  nature  of  a 
specific  infectious  disease,  but  none  of  which,  with 
the  possible  exception  of  calf  diphtheria,  tends  to 
be  reproduced  regularly,  in  typical  form,  by  arti- 
ficial means. 

In  swine,  B.  necrophorus  may  be  the  primary, 
and  usually  is  the  exciting  cause  of  various  ne- 
croses which  appear  in  the  mouth,  stomach  and 
intestines,  nasal  passages,  skin,  and  lungs,  and 
are  designated,  respectively,  according  to  loca- 
tion, necrotic  stomatitis,  enteritis,  rhinitis  (bull 
nose),  dermatitis  and  pulmonary  bacillosis.  The 
typical  lesion  consists  of  a  dark  brown  necrotic 
patch  which  spreads  slowly  and  tends  to  penetrate 
the  deeper  structures.  Frequently  a  yellowish- 
brown  scab  or  false  membrane  is  formed.  In  ne- 
crotic stomatitis  and  enteritis  especially,  numer- 
ous lesions  often  coalesce  until  large  areas  are  af- 
fected, and,  depending  on  location,  even  the  man- 
dible itself  may  be  involved  or  the  intestinal  wall 
penetrated.  A  foul  odor  is  usually  detected.  In 
the  mouth,  the  lesions  usually  take  origin  from 
teething  wounds  or  other  slight  abrasions ;  in  the 
stomach  and  intestines,  hog  cholera  lesions  and 
various  irritants  prepare  the  ground  for  their 
development;  in  the  nasal  passages  they  follow 
rhinitis  due  to  other  causes ;  in  the  skin,  they  ap- 
pear especially  on  the  teats  and  udders  of  sows 


32  HOG   CHOLERA 

which  are  chapped  or  wounded  as  a  result  of  nurs- 
ing litters.  We  know  less  regarding  the  primary 
cause  of  necrotic  lesions  that  appear  in  the 
lungs. 

It  is  still  an  open  question  whether  B.  necropho- 
rus  is  really  capable  of  penetrating  normal  mu- 
cous membrane  and  producing  its  characteristic 
effects,  but  usually  it  does  not.  Likewise  there  is 
doubt  as  to  whether  it  releases  a  toxin,  the  prob- 
ability being  that  at  times  it  does,  for  especially  in 
young  pigs  suffering  with  necrotic  stomatitis, 
death  often  takes  place  suddenly,  before  it  can  be 
explained  on  the  basis  of  the  existing  local  lesion. 
On  the  other  hand,  some  pigs  will  harbor  surpris- 
ingly extensive  lesions  without  marked  systemic 
disturbances.  Some  regard  B.  necrophorus  as  a 
secondary  invader  that  may  cause  the  "button 
ulcers "  which  appear  in  chronic  hog  cholera,  but 
there  is  at  least  a  distinct  difference  between  the 
button  ulcer  in  which  degenerative  and  regenera- 
tive processes  coexist,  and  the  usual  lesion  pro- 
duced by  B.  necrophorus,  in  which  a  progressive 
necrosis  prevails  as  long  as  the  exciting  cause  re- 
mains active.  There  is  also  somewhat  meager 
evidence  that  the  organism  may  in  rare  instances 
cause  petechial  hemorrhages  in  the  serous  mem- 
branes and  kidneys. 

Bact.  suisepticum,  B.  suipestifer,  B.  pyocya- 
neus,  and  Bact.  necrophorus  have  two  characteris- 


COMPLICATIONS  33 

tics  in  common.  All  are  of  a  subvirulent  nature, 
usually  depending  on  other  influences  or  predis- 
posing causes  to  enable  them  to  exert  their  patho- 
genic powers,  and  all  frequently  take  advantage 
of  the  lesions  produced  by  hog  cholera  virus,  in 
which  they  establish  themselves,  changing  the 
course  of  the  disease,  and  rendering  autopsies 
puzzling  and  inconclusive. 

There  are  several  other  organisms  that  have 
been  associated  with  hog  cholera,  either  as  com- 
plicating influences  or  probable  causes,  but  some 
of  these  normally  lead  a  saprophytic  existence, 
and  with  our  present  knowledge  we  are  unable  to 
assign  to  any  one  of  them  a  definite  pathogenic 
role.  B.  coll  communis  and  other  members  of  the 
group,  together  with  various  streptococci  and 
micrococci  may  often  be  found  in  lungs  of  hogs 
that  have  died  of  a  terminal  pneumonia  brought 
on  by  hog  cholera.  Spirochceta  lnyos  (King)  is 
sometimes  found  in  the  blood  and  intestinal  le- 
sions of  hogs  suffering  with  cholera,  and  B.  py- 
ogenes  suis  is  found  in  various  suppurating  lesions 
in  swine,  some  of  which  have  died  in  hog  cholera 
outbreaks.  The  collective  primary  and  secondary 
effects  of  all  the  organisms  considered  in  this 
chapter,  together  with  the  changes  produced  by 
hog  cholera  virus  go  to  make  up  the  symptom- 
complex  which,  conveniently  but  unfortunately, 
has  come  to  be  known  as  "  mixed  infection, "  and 


34  HOG    CHOLERA 

handled  as  a  single  entity.  Only  when  we  begin 
to  inquire  more  closely  into  the  disease-producing 
powers  of  each  organism  will  real  progress  be 
made. 


CHAPTER  V 

SYMPTOMS   AND   LESIONS 

FOLLOWING  the  subcutaneous  injection  of  a 
small  quantity  of  hog  cholera  virus,  or  the  feeding 
of  material  containing  it,  symptoms  of  the  disease 
usually  appear  between  the  fifth  and  eighth  days. 
In  herds  through  which  the  disease  is  spreading, 
several  weeks  are  often  required  for  it  to  reach 
all  individuals,  but  this  delay  must  be  regarded 
as  due  to  failure  of  some  of  the  hogs  to  take  up  the 
virus,  rather  than  as  a  prolonged  incubation 
period.  The  incubation  period  usually  given  va- 
ries between  four  and  twenty-one  days,  but  in  the 
vast  majority  of  cases  symptoms  will  appear  in 
less  than  nine  days  following  definite  exposure 
(feeding  or  inoculation)  of  susceptible  pigs. 

Three  forms  of  hog  cholera  are  recognized,  per- 
acute,  acute  and  chronic.  The  peracute  form  is 
relatively  infrequent,  but  it  occurs  occasionally 
among  the  first  few  hogs  that  succumb  in  an  out- 
break. No  definite  symptoms  have  been  asso- 
ciated with  this  form  of  the  disease,  for  the  af- 
fected animals  are  found  dead  with  no  history  of 
previous  sickness. 

35 


36  HOG   CHOLERA 

The  acute  form,  which  includes  the  great  ma- 
jority of  cases,  begins  with  high  fever  (105°-109° 
F.),  arched  back,  chilling,  rough  coat,  drooping 
ears  and  tail,  and  general  depression.  The  appe- 
tite is  impaired.  The  affected  animals  may  crowd 
to  the  trough  in  the  usual  greedy  fashion,  but 
after  drinking  sparingly  of  any  liquid  that  may  be 
contained  in  the  feed,  they  return  languidly  to 
the  nest  in  advance  of  their  associates,  slowly 
draw  the  litter  backward  with  alternating  fore- 
feet, and  then  settle  to  sternal  recumbency  with 
the  snout  hidden  beneath  the  litter,  seemingly  in 
an  effort  to  keep  warm.  Intermittent  attacks  of 
chilling  shake  the  body,  the  reflexes  are  dulled, 
the  eyes  closed,  and  a  general  stupor  prevails. 

Conjunctivitis,  mild  or  severe,  is  practically  al- 
ways present,  causing  an  exudate  of  a  seromucous 
or  seropurulent  type  to  appear,  gumming  the  eye- 
lids together,  or  forming  crusts  which  remain  in 
the  internal  canthus  and  on  the  margins  of  the 
lids. 

Early  in  the  attack,  constipation  is  noted.  The 
fecal  balls,  usually  dark  in  color  and  often  cov- 
ered with  mucus,  are  voided  with  difficulty. 
Later,  if  death  does  not  ensue,  diarrhea  sets  in, 
and  continues  pending  the  advent  of  death  or  con- 
valescence. The  character  of  the  food  determines 
the  color  of  the  feces. 

As  the  sick  hog  lies  undisturbed  in  the  nest 


37 


38  HOG    CHOLERA 

there  is  often  noted  a  scarcely  audible,  high- 
pitched,  complaining  expiratory  grunt,  but  if  the 
animal  is  seized  suddenly  it  struggles  feebly  and 
emits  a  weak,  hoarse  squeal.  The  gait  may  be 
unchanged,  but  often  staggering  is  noticed,  and 
sometimes  there  is  a  characteristic  unsteadiness 
or  weaving  in  the  hind  quarters,  best  observed  in 
well  advanced  cases  when  the  animals  are  caused 
to  move  without  undue  excitement. 

Convulsions  appear  somewhat  infrequently,  and 
may  be  regarded  as  the  only  violent  hog  cholera 
symptom.  The  attack  usually  occurs  at  feeding 
time  or  under  stress  of  other  excitement,  more 
often  in  young  pigs.  The  pig  comes  to  the  trough 
as  if  to  eat,  but  suddenly  backs  away,  squealing, 
with  the  snout  drawn  low  between  the  forelegs. 
The  muscles  stiffen  in  spasm,  the  pig  falls  on  its 
side,  the  eyeballs  roll  upward,  the  legs  are  in  con- 
stant motion,  and  the  snout  is  gradually  extended 
with  a  jerky,  convulsive  movement.  The  attack 
lasts  less  than  a  minute  and  terminates  either  in 
death  or  complete  return  of  nervous  function. 

Early  in  an  attack  of  hog  cholera,  the  skin  is 
flushed,  hot  and  sensitive,  the  flush  being  appar- 
ent only  in  clean  white  pigs.  Later,  as  death  ap- 
proaches, a  diffuse  purplish  discoloration  some- 
times appears  in  the  skin  covering  the  ears,  snout, 
belly  and  inner  surfaces  of  the  legs,  and  is  less 
frequently  observed  at  the  extremity  of  the  tail, 


SYMPTOMS   AND   LESIONS  39 

on  the  vulva,  and  in  the  perineal  region.  Depend- 
ing on  whether  the  color  results  from  hyperemia 
or  hemorrhage,  it  will  or  will  not  disappear  on 
pressure.  Sometimes  congestion  and  hemorrhage 
coexist,  in  which  case  the  color  disappears  for  the 
most  part,  revealing  the  presence  of  ecchymoses 
in  the  pressure-whitened  area.  Less  frequently 
ecchymoses  exist  alone.  Somewhat  infrequently 
skin  ulcers  appear  on  the  throat  and  between  the 
forelegs,  very  rarely  elsewhere  on  the  body. 
They  are  light  brown,  irregularly  round  or  oval 
in  shape,  %-2  centimeters  in  diameter,  and  cov- 
ered with  scabs.  A  rusty  yellow,  very  sticky  exu- 
date,  most  apparent  on  the  ventral  scantily-haired 
body  surfaces,  is  noted  in  some  individuals. 

Cough  is  observed  in  many  field  outbreaks,  but 
it  is  by  no  means  a  constant  symptom  in  uncom- 
plicated hog  cholera.  We  have  failed  to  establish 
a  definite  relation  between  this  symptom  and  the 
petechial  hemorrhages  which  appear  in  the  laryn- 
geal  mucosa.  Respiratory  symptoms  are  not 
prominent  in  hog  cholera  unless  it  is  complicated 
with  pneumonia,  but  dyspnea  develops  frequently 
under  forced  exertion. 

The  superficial  inguinal  lymph  glands  are  fre- 
quently enlarged  so  as  to  attract  attention,  and 
another  common  symptom  is  the  collection  of  urine 
in  the  sheath  of  the  male  pig,  causing  marked  dis- 
tention.  When  pressed  out  manually,  the  urine 


40  HOG   CHOLERA 

has  a  very  offensive  odor,  and  may  be  cloudy  white 
in  appearance,  or  otherwise  abnormal. 

As  the  disease  progresses,  emaciation  is  quite 
rapid,  and  general  weakness  prevails.  Frequently 
a  terminal  pneumonia  develops  during  the  last 
few  hours,  and  death  may  result  from  heart  or 
respiratory  failure. 

Chronic  hog  cholera  occurs,  for  the  most  part, 
among  stragglers  that  survive  the  acute  form,  but 
it  may  exist  independently  among  semisusceptible 
young  pigs.  Emaciation,  cough,  depraved  appe- 
tite, diarrhea,  unsteady  gait,  drooping  ears  and 
tail,  tucked-up  flank,  and  even  sloughing  of  the 
skin  are  among  the  symptoms  that  appear.  Some 
animals  recover,  but  complete  return  to  normal 
health  is  not  the  rule. 

LESIONS 

Peracute  hog  cholera  does  not  usually  produce 
characteristic  macroscopic  lesions,  but  congestion 
of  the  lymph  glands,  mesenteric  vessels  and  var- 
ious parenchymatous  organs  may  often  be  ob- 
served. It  is  in  the  acute  uncomplicated  form 
that  the  most  typical  lesions  occur.  These  con- 
sist of  congestion,  hemorrhages  and  degeneration, 
hemorrhages  being  the  only  ones  which,  by  virtue 
of  character  or  location,  are  highly  characteristic 
of  the  disease.  These  appear  as  petechiae  in  the 
kidneys,  serosa  of  the  intestines,  mucosae  of  the 


SYMPTOMS   AND   LESIONS  41 

bladder  and  larynx,  in  the  pericardium,  epicar- 
dium,  and  on  the  auricles  of  the  heart,  especially 
the  left.  Exceptionally  they  are  seen  in  the  dia- 
phragm, in  the  parietal  pleura  and  peritoneum, 
and  subjacent  connective  tissue.  In  the  lungs,  the 
hemorrhages  usually  appear  beneath  the  pleura 
as  ecchymoses,  more  often  in  the  ventral  portions 
of  the  cephalic  and  cardiac  lobes,  but  at  other 
times  unconfined  to  particular  areas.  In  the 
spleen  they  appear  as  well-defined  slightly  raised 
black  areas  %  to  1%  centimeters  in  diameter, 
practically  always  at  the  edge  of  the  organ  and 
visible  beneath  its  capsule  from  the  dorsal  aspect. 
Some  of  the  lymph  glands  are  practically  always 
congested  or  hemorrhagic.  The  hemorrhage  ap- 
pears first  around  the  periphery  as  the  sectioned 
surface  will  show,  later  extending  to  the  trabec- 
ulae,  and  finally  in  some  cases  progressing  so  far 
that  the  entire  structure  becomes  infiltrated,  show- 
ing on  section  a  uniform  dark  color.  Petechiae 
and  ecchymoses  in  the  lymph  glands  are  excep- 
tional. The  nodes  most  regularly  involved  in- 
clude the  gastric,  hepatic,  lumbar,  superficial  in- 
guinal, mediastinal  and  submaxillary. 

The  hemorrhages  which  are  found  in  and  be- 
neath the  alimentary  mucosa  may  appear  in  the 
form  of  petechiae  or  ecchymoses,  but  there  is  a 
marked  tendency,  due  probably  to  constant  me- 
chanical irritation,  for  them  to  become  more 


42  HOG   CHOLEEA 

diffuse  in  character.  The  pharynx  and  esophagus 
are  rarely  affected,  the  stomach  and  small  intes- 
tines frequently  are,  while  the  mucosa  of  the 
cecum  and  upper  colon  usually  is  involved. 

The  skin  lesions  may  consist  of  congestion  or 
hemorrhage  of  circumscribed  or  diffuse  nature, 
the  latter  type  being  by  far  the  most  common,  and 
appearing  as  a  purplish  discoloration  usually  con- 
fined to  the  ears,  belly,  snout,  inner  surfaces  of 
the  legs,  tip  of  tail,  vulva,  and  perineal  region. 
Small  skin  ulcers  less  than  two  centimeters  in 
diameter,  irregularly  round  or  oval  in  shape, 
brown  in  color  and  scabbed  over,  appear  somewhat 
infrequently  on  the  throat,  very  exceptionally 
elsewhere  on  the  body.  These  seemingly  take 
origin  from  previous  hemorrhages. 

Some  have  considered  all  these  changes  as  due 
to  secondary  invasion,  holding  to  the  belief  that 
hog  cholera  virus  in  itself  does  not  produce  mac- 
roscopic lesions.  To  this  view  we  are  unable  to 
subscribe,  for  one  may  transport  filtered  virus 
hundreds  of  miles,  and  it  will  still  produce,  regu- 
larly, some  or  all  of  the  leions  just  described,  and 
it  is  inconceivable  that  the  same  secondary  in- 
fluences should  be  present  in  all  localities. 

In  order  to  place  in  relief  the  more  character- 
istic macroscopic  lesions  which,  according  to  our 
conception,  are  due  usually  to  unaided  action  of 
the  filterable  hog  cholera  virus,  we  have  for  the 


SYMPTOMS    AND   LESIONS  43 

moment  neglected  discussion  of  less  characteris- 
tic changes  which  frequently  take  place.  If  we 
consider  each  organ  separately,  extending  our  ob- 
servations to  include  less  characteristic  changes, 
as  well  as  those  produced  by  secondary  invaders 
discussed  in  a  previous  chapter,  a  more  complete 
picture,  and  a  more  accurate  interpretation1  of  the 
pathological  anatomy  encountered  in  field  cases 
can  be  presented. 

Mouth  and  pharynx.  Mucosa  usually  normal. 
Hog  cholera  virus  may  be  primary  cause  of  ulcers. 
These  are  sometimes  present  in  hog  cholera  out- 
breaks, and  appear  as  dark  brown  necrotic  patches 
on  gums,  lips,  tongue  and  other  parts.  Probably 
due  to  primary  injuries  caused  by  the  filterable 
virus,  and  certainly  caused  by  B.  necrophorus  as 
a  secondary  invader.  B.  necrophorus  ulcers  oc- 
cur independent  of  filterable  virus  infection. 

Stomach.  Mucosa  frequently  normal.  Filter- 
able virus  causes  petechise,  ecchymoses  or  larger 
suffusions  in  fundus.  Congestion  due  to  the  same 
cause  usually  present.  Ulceration  relatively  rare, 

1  We  are  fully  aware  that  with  our  present  knowledge  such  an 
interpretation  can  be  only  approximately  correct,  but  nevertheless 
there  are  certain  well-defined  tendencies  which  should  be  indicated. 
Our  conception  of  the  primary  filterable  virus  lesion  has  been 
gained,  during  the  last  ten  years,  by  performing  autopsies  on 
hundreds  of  pigs  which  were  killed  about  a  week  subsequent  to 
injection  with  virus.  The  virus  was  obtained  from  several  sources 
in  various  states,  some  was  filtered,  some  was  not.  We  have  also 
investigated  several  of  the  secondary  invaders,  and  the  combined 
results  of  these  investigations  with  those  of  similar  nature  con- 
ducted by  other  workers,  are  reflected  in  the  remarks  which  follow. 


44  HOG   CHOLERA 

but  necrotic  patches  due  to  secondary  infection 
with  Bact.  necrophorus  may  appear.  Serosa  usu- 
ally normal.  Exceptionally  studded  with  puncti- 
form  hemorrhages,  due  to  filterable  virus. 

Small  intestine.  Mucosa  sometimes  normal. 
Congestion  rather  common,  also  hemorrhages  sim- 
ilar to  those  observed  in  stomach,  and  due  to  filter- 
able virus.  Lymphoid  nodules  often  congested, 
less  frequently  hemorrhagic,  due  to  filterable  vir- 
us. Those  in  ilium  most  frequently  involved. 
Ulceration  rather  uncommon,  except  in  extreme 
posterior  portion  of  ileum.  Serosa  usually  nor- 
mal. Petechial  hemorrhages  appear  infrequently, 
mesentery  often  congested.  Changes  due  to  filter- 
able virus. 

Caecum  and  upper  colon.  Mucosa  most  con- 
stant seat  of  digestive  canal  lesions,  especially 
region  of  iliocecal  valve.  Congestion,  petechise, 
ecchymoses1  and  larger  suffusions  common. 
Strong  tendency  toward  ulceration.  Pitlike 
patches  denuded  of  epithelium.  Necrotic  ulcers 
or  patches,  dark  brown  in  color,  sometimes  false 
membrane ;  ulcers  tending  to  broaden  and  deepen, 
little  tendency  toward  regeneration.  "  Button 
ulcers ' ' 1  occur  in  chronic  hog  cholera.  Serosa 

1  The  ulcers  may  be  isolated  and  appear  as  circular,  slightly 
projecting  masses  stained  yellowish  or  blackish  or  both  in  alter- 
nate rings,  or  they  may  be  slightly  depressed  and  somewhat  ragged 
in  outline.  When  the  superficial  slough  is  scraped  away  many 
ulcers  show  a  grayish  or  white  base.  A  vertical  section  reveals  a 
rather  firm  neoplastic  growth,  extending  usually  to  the  inner  mus- 


SYMPTOMS    AND   LESIONS  45 

often  normal,  petechiae  not  infrequent.  Hemor- 
rhages and  destruction  of  epithelial  cells  probably 
due  to  filterable  virus.  "Button  ulcers "  due  to 
B.  suipestifer,  possibly  to  other  organisms. 
Necrotic  patches  usually  due  to  Bact.  necro- 
phorus. 

Lower  colon  and  rectum.  Usually  normal  or 
nearly  so.  Sometimes  congested.  Infrequently 
the  lower  colon  shows  the  same  change  as  the 
upper  colon. 

Larynx.  Mucosa  frequently  normal.  Some- 
times congested,  more  often  dotted  with  petechiae 
caused  by  filterable  virus. 

Trachea  and  bronchi.  Mucosa  often  normal. 
Sometimes  congested.  Probably  due  to  filterable 
virus. 

Lungs.  Very  often  normal.  Primary  lesions 
sometimes  caused  by  filterable  virus  consist  of 
ecchymoses  visible  beneath  the  pleura.  These  ap- 
pear most  frequently  on  the  cephalic  and  cardiac 
lobes,  but  are  not  confined  to  these  parts. 

Terminal  pneumonia  due  to  filterable  virus  plus 
nonspecific  secondary  invaders.  Often  affects  all 

cular  coat.  When  sections  of  such  an  ulcer  are  stained  with 
aniline  dyes  and  examined  under  the  microscope,  the  submucous 
tissue  is  very  much  thickened,  infiltrated  with  round  cells  and  con- 
taining a  large  number  of  dilated  blood  vessels.  Eesting  upon 
this  thickened  submucosa,  is  a  line  of  very  deeply  stained  amor- 
phous matter,  and  upon  this  is  situated  the  necrotic  mass  which 
fails  to  retain  the  coloring  matter  and  which  is  permeated  by  a 
very  large  number  of  bacteria  of  various  kinds.  Frequently  the 
eggs  of  trichocephalus  are  imbedded  in  the  slough." — Moore, 
Pathology  of  Infectious  Diseases. 


46 


HOG    CHOLERA 


lung  tissue.     Lung  solidified,  red.     Pneumonia  of 
recent  origin. 

Swine  plague  pneumonia  due  to  filterable  virus 


PLATE  2.     Lung    of    pig    showing    ecchymoses    due    to    acute    hog 

cholera.     These  appear  in  greater  numbers  on  the 

apical  and  cardiac  lobes 

plus  Bad.  suisepticum.  Cephalic  and  cardiac 
lobes  first  to  be  affected,  later  other  parts  may 
solidify.  Solidified  portion  usually  red  or  reddish 
gray.  Usually  bronchopneumonia.  Interlobular 


SYMPTOMS    AND   LESIONS  47 

spaces  well  defined  macroscopically,  due  to  infil- 
tration of  leucocytes  or  blood.  Tendency  toward 
necrotic  and  caseous  masses  in  cases  of  longer 
standing.  Pleuritis  constant.  Pleurae  often 
thickened,  rough,  white,  adherent. 

Pneumonia,  characterized  by  necroses  which 
start  from  various  foci,  tending  to  involve  all 
structures  alike,  sometimes  spreading  to  the  heart 
by  contiguity.  Filterable  virus  plus  Bact.  necro- 
phorus. 

Pneumonia,  often  semichronic,  tending  toward 
formation  of  multiple  abscesses  visible  beneath 
the  pleura,  as  slightly  raised,  yellow  areas.  Visi- 
ble on  section  in  deeper  parts.  Pneumonic  lung 
may  be  red.  More  often  grayish  in  color.  Due 
to  filterable  virus  plus  B.  pyocyaneus* 

Heart.  Usually  normal.  Filterable  virus  le- 
sions consist  of  petechiae  and  ecchymoses  which 
are  visible  on  the  surfaces  of  the  auricles,  usually 
the  left.  Sometimes  congestion  of  coronary  ves- 
sels. Heart  itself  rarely  the  seat  of  secondary  le- 
sions. Epicarditis  and  pericarditis  often  result 
from  secondary  infection  with  Bact.  suisepticum. 

Spleen.  Sometimes  normal  or  slightly  en- 
larged. Very  small  bright-red  protruding  hem- 

aHog  cholera  virus  is  only  one  of  several  influences  capable  of 
producing  primary  changes  which,  in  the  presence  of  secondary- 
invasion  with  either  Bact.  necrophorus  or  B.  pyocyaneus  may  re- 
sult in  the  lung  lesions  mentioned  in  connection  with  these  organ- 
isms. For  instance,  we  regard  lung  worms  in  combination  with 
B.  pyocyaneus  as  a  frequent  cause  of  pneumonia  in  pigs. 


48 


PLATE  4.  Spleens  showing  hemorrhages  which  are 
rather  typical  of  acute  hog  cholera.  These 
hemorrhages  are  observed  in  only  a  small  per- 
centage of  cases 

49 


50  HOG    CHOLEKA 

orrhages  beneath  capsule  are  normal.  These  are 
frequently  on  ventral  surface  near  the  hilus,  not 
so  often  along  the  borders  and  on  the  dorsal  sur- 
face. Characteristic  filterable  virus  lesions  con- 
sist of  black,  well  defined  slightly  raised  hemor- 
rhages %  to  2  centimeters  in  diameter,  located 
practically  always  somewhere  on  the  margin. 
Spleen  may  be  enlarged,  dark,  friable,  engorged 
with  blood.  Due  usually  to  secondary  invasion 
with  B.  suipestifer,  sometimes  to  other  causes. 
Not  of  much  diagnostic  value  as  related  to  hog 
cholera. 

Liver.  Macroscopic  appearance  usually  nor- 
mal. Very  exceptionally  ecchymoses,  seemingly 
due  to  hog  cholera  virus,  are  visible  beneath  the 
capsule.  Often  shows  degenerative  changes, 
probably  due  to  hog  cholera  virus,  but  by  no  means 
characteristic,  as  they  may  be  due  to  a  variety  of 
causes. 

Kidney.  Very  rarely  normal.  Seat  of  the 
most  characteristic  and  constant  hog  cholera  le- 
sions, consisting  of  petechiae.  Organ  may  be 
changed  as  follows: 

Normal  in  color,  capsule  peels  easily.  Surface 
of  kidney  studded  with  petechiae  which  appear 
beneath  the  capsule,  involving  the  glomeruli  as 
well  as  other  parts.  On  section,  the  petechiae  are 
seen  variously  distributed  in  the  cortex,  in  the 
medulla,  and  sometimes  in  the  membrane  of  the 


PLATE  5.  Kidney  of  pig  showing  numerous 
petechiae  due  to  acute  hog  cholera.  Often 
these  petechiae  are  so  small  and  few  in  num- 
ber that  it  is  necessary  to  examine  the  kid- 
ney very  closely  in  a  good  light  in  order  to 
observe  them.  The  capsule  is  removed  in 
order  to  make  them  more  plainly  visible 

n 


52  HOG    CHOLEBA 

renal   pelvis.     They    are    du-9    to    the    filterable 
virus. 

Engorged  with  blood.  Capsule  peels  easily. 
Petechiae  distributed  as  already  described.  Tend- 
ency toward  more  and  larger  hemorrhages. 
Changes  usually  due  to  filterable  virus.  Bact. 
suisepticum  or  B.  cholera  suis  may  be  secondary 
invaders. 

Very  light  in  color,  "  cooked  kidney. "  Capsule 
peels  easily.  Marked  evidences  of  degeneration. 
(Cloudy  swelling  and  granular  degeneration.) 
Petechiae  distributed  as  already  described.  All 
changes  probably  due  to  filterable  virus. 

Very  light  in  color.  Capsule  peels  easily.  No 
petechiae.  Seen  most  frequently  in  chronic  hog 
cholera.  Changes  often  due  to  filterable  virus, 
but  not  characteristic  of  it. 

Very  light  in  color.  Capsule  peels  with  diffi- 
culty, may  be  thickened.  Evidences  of  degenera- 
tion followed  by  increase  in  interstitial  tissue,  and 
chronic  nephritis.  Primary  degeneration  prob- 
ably due  to  filterable  virus.  Nephritis  due  to  sec- 
ondary causes.  All  of  these  changes  of  little 
diagnostic  significance. 

Considered  in  general,  these  petechial  hemor- 
rhages, in  the  kidney  are  rarely  due  to  influences 
other  than  hog  cholera  virus.  Exceptionally  they 
may  be  due  to  Bact.  suisepticum,  acting  either  as 


SYMPTOMS    AND   LESIONS  53 

a  primary  or  secondary  influence.  There  is  a 
tendency  by  no  means  constant,  and  of  little  diag- 
nostic significance,  for  larger  and  less  well  defined 
hemorrhages  to  appear  under  the  influence  of 
Bact.  suisepticum.  There  is  also  some  evidence, 
as  yet  poorly  substantiated,  that  very  exception- 
ally Bact.  necrophorus  produces  petechiae  in  the 
kidneys  of  hogs.  This  should  be  regarded  as  a 
remote  possibility  occurring  only  in  association 
with  extensive  necrotic  lesions  in  other  organs. 

Bladder.  Sometimes  normal.  Mucosa  slightly 
congested,  due  to  hog  cholera  virus  or  other 
causes.  Mucosa  dotted  with  petechiae,  due  usu- 
ally to  hog  cholera  virus. 

Sheath.  Often  normal.  Sometimes  distended 
with  foul  smelling,  discolored  urine.  Catarrhal 
inflammation  of  mucosa.  Condition  not  charac- 
teristic of  hog  cholera.  Found  in  other  diseases, 
especially  those  resembling  rheumatism. 

Lymph  glands.  Sometimes  normal.  Typical 
filterable  virus  lesion  consists  of  congestion  or 
hemorrhage  which  appears  first  in  the  cortex  of 
the  gland,  and  which  may  later  involve  the  entire 
structure  giving  it  a  uniform  dark  color  on  section. 
Petechiae  are  rarely  present.  Edema  frequently 
pronounced.  Permanent  enlargement  and  casea- 
tion  occur  in  chronic  hog  cholera.  Rare  for  all 
glands  to  show  macroscopic  changes.  Glands 


54 


HOG    CHOLEEA 


most  frequently  affected  are  the  gastrics,  hepatics, 
superficial  inguinals,  lumbars,  submaxillaries  and 
mediastinals. 


PLATE  6.  Lymph  glands  of  pig  showing  hemorrhages  caused  by  acute  hog 
cholera.  Left,  darkened  surfaces  of  glands.  Above,  sectioned  surface 
showing  hemorrhages  around  the  periphery  and  in  the  sinuses.  Eight, 
darkened  gland  with  small  section  cut  away  to  show  peripheral 
hemorrhages 

Skin.  Often  normal.  Typical  filterable  virus 
lesions  consist  of  purplish  discoloration,  repre- 
senting marked  congestion  or  diffuse  hemor- 


SYMPTOMS    AND   LESIONS  55 

rhage.  Ecchymoses  more  rarely  visible.  Ulcers, 
apparently  originating  in  these  ecchymoses  some- 
times occur  on  throat  and  between  forelegs.  (In 
hot  weather  purple  discoloration  appears  a  few 
hours  after  death  in  hogs,  especially  fat  ones, 
dead  from  any  cause.) 

The  pathology  and  microscopic  tissue  changes 
produced  by  hog  cholera  virus  are  not  well  worked 
out,  but  nevertheless  the  relation  between  primary 
filterable  virus  lesions  and  secondary  changes  due 
to  other  causes  is  fairly  well  understood.  Let  us 
consider,  for  instance,  lesions  of  the  digestive  mu- 
cosa.  Congestion  appears  first.  It  will  disap- 
pear or  terminate  in  hemorrhage.  Following 
hemorrhage,  regenerative  or  degenerative  pro- 
cesses will  occur.  The  degenerative  processes 
may  result  in  destruction  and  excoriation  of  the 
epithelial  cells,  leaving  an  unprotected  surface  in 
contact  with  the  intestinal  contents.  Individual 
resistance  and  the  bacterial  flora  of  the  intestine 
will  determine  future  developments.  Regenera- 
tion will  rule,  or  secondary  infection  will  take 
place.  If  Bact.  necrophorus  is  present  in  suffi- 
cient numbers,  necrotic  enteritis  will  be  produced. 
If  B.  suipestifer  exists  in  overpowering  numbers, 
the  familiar  "  button  ulcer  "  may  develop. 

In  the  intestine,  we  find  the  primary  lesions  due 
to  the  filterable  virus  most  frequently  in  the  cse- 


56  HOG   CHOLERA 

cum  and  upper  colon,  and  as  would  be  expected, 
we  find  the  secondary  lesions  distributed  in  pre- 
cisely the  same  manner.  If  we  examine  a  hog 
dead  of  cholera  after  a  short  sickness  we  encoun- 
ter intestinal  lesions  in  which  congestion,  hemor- 
rhages and  early  evidences  of  degeneration  pre- 
dominate. In  hogs  that  have  been  sick  longer, 
autopsies  often  reveal  a  surprising  variety  of  le- 
sions which  collectively  encompass  effects  of  the 
struggle  between  degenerative  and  regenerative 
forces,  and  which  reach  their  most  typical  form  in 
the  "button  ulcer. " 

In  considering  thoracic  lesions,  the  same  general 
principles  apply.  If  we  inject  a  pig  with  filtered 
hog  cholera  virus,  and  kill  it  about  seven  days 
later,  the  lungs,  if  affected,  will  show  petechiae 
and  ecchymoses,  most  likely  appearing  on  the 
cephalic  and  cardiac  lobes,  but  not  always  confined 
to  these  parts.  There  may  also  be  congestion  of 
the  mucosa  of  the  air  passages.  Both  changes 
are  due  to  the  filterable  virus.  What  result 
would  we  expect  if  a  secondary  invader,  capable 
of  producing  inflammatory  changes,  should  find 
its  way  into  lesions  thus  prepared?  Obviously  we 
would  expect  to  find  bronchopneumonia,  occurring 
most  regularly  in  the  cephalic  and  cardiac  lobes 
but  not  always  thus  limited.  It  is  significant  that 
this  is  the  exact  picture  presented  when  secondary 
infection  with  Bact.  suisepticum  takes  place. 


SYMPTOMS   AND   LESIONS  57 

The  urine  of  hogs  suffering  with  cholera  often 
contains  albumin  in  excessive  amounts,  and  the 
chlorids  frequently  are  diminished  in  quantity,  or 
present  only  in  traces.  Contrary  to  what  might 
be  expected,  blood  and  hemoglobin  are  absent,  al- 
most without  exception. 


CHAPTER  VI 

DIAGNOSIS,  DIFFERENTIAL  DIAGNOSIS,  PKOGNOSIS 

EARLY  and  correct  diagnosis  of  hog  cholera  is 
essential  in  coping  with  the  disease  effectively. 
Often  an  entire  herd  is  in  jeopardy,  and  if  hog 
cholera  is  present  prompt  preventive  measures 
must  be  taken  to  save  it.  The  diagnosis  involves 
no  great  difficulties  when  many  hogs  are  sick,  but 
in  the  early  days  of  an  outbreak  when  peracute 
or  otherwise  atypical  cases  are  likely  to  occur, 
puzzling  situations  arise  which  sometimes  cause 
costly  delay.  Thus  in  exceptional  cases  we  are 
justified  in  making  a  provisional  diagnosis  of  hog 
cholera,  and  in  handling  the  herd  in  exactly  the 
same  manner  as  we  would  were  a  positive  diagno- 
sis possible.  Experience  has  taught  that  we 
should  not  be  too  conservative  in  regard  to  taking 
such  a  course  when  the  history  suggests  the  dis- 
ease and  when  valuable  animals  are  at  stake. 

In  seeking  to  determine  the  presence  of  hog 
cholera  we  depend  on  four  considerations: 

1.  History  of  the  outbreak. 

2.  Symptoms. 

3.  Lesions. 

58 


DIAGNOSIS,    DIFFEBENTIAL   DIAGNOSIS,   PROGNOSIS        59 

4.  Animal  Inoculation  (rarely  applicable). 

History.  Securing  the  history  of  an  outbreak 
of  suspected  hog  cholera  is  simply  applying  knowl- 
edge of  the  ways  in  which  the  virus  spreads. 
Usually  we  find  that  a  hog  has  died  of  an  unknown 
cause  and.  a  few  days  later  sickness  has  appeared 
among  its  associates.  Careful  inquiry  should  be 
made  regarding  recent  introduction  of  hogs  into 
the  herd,  existence  of  swine  disease  in  the  vicinity, 
adjacent  arteries  of  traffic  and  source  of  feed  and 
water  supply.  Stockyard  hogs  and  others  intro- 
duced without  clear  history  of  previous  health 
should  remain  under  suspicion.  Even  though 
they  do  not  themselves  contract  the  disease  they 
may  act  as  intermediate  carriers.  There  is  no 
evidence  that  hog  cholera  virus  travels  through 
the  air  but  a  road  or  railroad  right-of-way  may  be 
contaminated  by  the  drip  from  infected  wagons  or 
cars.  If  the  herd  is  subsisting  on  garbage  and  is 
not  immune  the  circumstances  suggest  hog  chol- 
era. If  kitchen  swill  is  being  fed  inquiry  should 
be  made  as  to  whether  the  kitchen  is  supplied  with 
market  pork.1 

In  general  the  facts  brought  out  by  the  history 
of  an  outbreak  simply  constitute  supplementary 

1  In  one  instance  that  came  under  our  observation  an  outbreak 
of  hog  cholera  was  traced  to  meat  trimmings  that  were  placed  in 
a  poultry  house.  Two  small  pigs  formed  the  habit  of  escaping 
from  the  pen  and  eating  freely  of  these  trimmings.  Both  devel- 
oped hog  cholera  simultaneously,  and  later  transmitted  it  to  their 
associates. 


60  HOG    CHOLERA 

evidence  tending  either  to  affirm  or  deny  the  pres- 
ence of  hog  cholera.  Unless  there  is  a  definite 
history  of  direct  exposure  the  history  in  itself  is 
not  conclusive. 

Symptoms.  Unless  several  animals  are  sick  it 
is  seldom  possible  to  make  a  positive  diagnosis 
based  on  symptoms  alone,  but  the  experienced  ob- 
server is  usually  fairly  certain  of  his  ground. 
It  is  essential  to  remember  that  early  in  an  out- 
break we  do  not  observe  the  greatly  emaciated 
hog  with  arched  back,  straight  tail  and  drooping 
ears  which  has  been  so  frequently  described  and 
photographed,  and  which  is  the  product  of  long 
sickness.  It  should  also  be  kept  in  mind  that 
many  of  the  symptoms  observed  in  acute  hog 
cholera  are  present  in  other  diseases,  and  that  all 
of  the  symptoms  that  characterize  the  disease,  do 
not  often  appear  in  one  animal.  Special  consid- 
eration must  be  given  to  a  restricted  number  of 
the  more  characteristic  symptoms. 

In  examining  a  herd  for  suspected  hog  cholera 
one  should  first  see  it  unaffected  by  artificial  ex- 
citement, taking  care  to  observe  a  tendency  in 
individuals  to  chill  and  crawl  beneath  the  litter. 
Then  the  animals  may  be  tempted  from  the  nest 
with  feed,  observation  being  made  for  any  that  are 
reluctant  to  move,  or  that  stagger  or  weave  in  the 
hind  quarters.  The  animals  that  come  greedily  to 
the  trough  but  leave  for  the  nest  in  advance  of 


DIAGNOSIS,    DIFFERENTIAL   DIAGNOSIS,    PROGNOSIS         61 

their  associates,  dropping  slowly  to  sternal  recum- 
bency with  their  snouts  half  buried  in  the  litter 
should  be  regarded  as  probable  cases  of  hog  chol- 
era, especially  when  intermittent  attacks  of  chill- 
ing are  observed. 

Temperature  is  an  important  guide,  but  great 
care  must  be  taken  in  securing  and  interpreting 
readings.  Normal  temperatures  of  hogs  vary  be- 
tween 101°  and  104°  F.  and  independent  of  dis- 
ease, excitement  or  exertion  causes  a  more  rapid 
temperature  elevation  in  swine  than  in  other  ani- 
mals. Docile  adult  breeding  animals  in  medium 
flesh  are  inclined  to  show  readings  near  101°  F., 
while  those  of  young  pigs  and  fat  hogs  tend  to  ap- 
proach 104°  F.  In  taking  temperatures  of  pigs, 
the  thermometer,  preferably  one  with  pear  or 
globe-shaped  bulb  and  at  least  five  inches  long, 
should  be  inserted  almost  full  length.  Otherwise 
many  inaccuracies  (readings  too  low)  will  occur, 
because  a  pig,  especially  if  held  by  the  hind  legs, 
will  often  relax  the  rectum  as  long  as  the  ther- 
mometer remains  in  position.  Chasing  pigs  to 
catch  them  often  elevates  their  temperatures 
rapidly,  and  should  be  avoided. 

It  is  important  to  keep  in  mind  the  usual  hog 
cholera  temperature  curve.  In  the  typical  case 
of  the  acute  form  of  the  disease  the  curve  rises 
rapidly  at  the  onset  of  the  attack  and  reaches 
an  elevation  between  106°  and  107°  F.  in  less  than 


62  HOG    CHOLERA 

forty-eight  hours.  This  level  is  maintained  for 
about  four  days  and  is  followed  by  a  sharp  decline 
which  may  bring  it  near  normal  for  a  few  hours. 
Then  there  is  an  upward  trend  which  carries  it 
near  the  former  high  level  in  which  position  it 
may  be  maintained,  or  it  may  fluctuate  somewhat 
violently  from  day  to  day.  Sometimes  it  remains 
elevated  until  death  takes  place,  but  usually  it 
sinks  below  normal  a  short  time  before  the  pig 
dies. 

Thus  it  is  always  well  to  secure  temperatures 
of  hogs  recently  affected,  and  to  be  cautious  in 
regard  to  making  a  negative  diagnosis  on  the 
strength  of  a  limited  number  of  temperatures  near 
normal.  Several  readings  near  or  above  106°  F., 
supported  by  other  suspicious  symptoms  and  a 
history  that  indicates  hog  cholera,  may  rightly 
form  the  basis  for  a  provisional  diagnosis.  On 
the  other  hand,  a  considerable  number  of  tempera- 
tures below  104°  F.  in  sick  hogs,  strongly  suggests 
some  other  disease.  Between  these  extremes  the 
readings  are  less  conclusive. 

In  this  country,  and  in  others  where  swine  ery- 
sipelas is  not  prevalent,  the  characteristic  diffuse 
purplish  discoloration  which  appears  on  the  belly, 
ears  and  snout  is  pathognomonic  of  hog  cholera, 
but  it  is  observed  in  relatively  few  cases.  If  this 
discoloration  is  not  observed  before  death  it  is 
of  no  significance,  for  it  may  occur  as  a  post-mor- 


DIAGNOSIS,   DIFFERENTIAL  DIAGNOSIS,   PROGNOSIS         63 

tern  change  in  swine  dead  from  any  cause,  es- 
pecially fat  hogs  that  have  died  in  hot  weather. 

Other  less  characteristic  symptoms  add  evi- 
dence, but  most  of  them  may  result  from  causes 
other  than  hog  cholera,  and  it  is  unsafe  to  give 
them  too  much  weight  in  their  relation  to  diagno- 
sis. 

Lesions.  Lesions  constitute  our  most  accurate 
guide  in  diagnosing  hog  cholera,  for  it  is  not  often 
that  a  conclusion  can  be  reached  without  consider- 
ing them.  Hogs  sometimes  die  of  the  disease 
without  showing  any  characteristic  macroscopic 
tissue  changes,  so  if  no  cause  for  death  is  found, 
additional  autopsies  should  be  performed.  In 
case  it  is  necessary  to  kill  a  pig  for  this  purpose, 
it  is  best  to  select  one  that  has  been  sick  several 
days,  but  not  a  chronic  case.  Petechiae  and  ec- 
chymoses  are  the  chief  changes  which  character- 
ize hog  cholera,  but  it  is  important  to  remember 
that  in  cases  of  long  standing,  and  in  those  in 
which  secondary  invasion  has  taken  place  these 
primary  filterable  virus  lesions  may  be  so  changed 
in  character  that  they  are  difficult  to  identify. 

Assuming  that  we  have  before  us  a  carcass,  and 
that  hog  cholera  is  suspected,  the  autopsy  will  in- 
clude special  examination  of  the  skin,  kidneys, 
bladder,  lymph  glands,  spleen,  heart,  lungs  and 
laryngeal  mucosa,  as  well  as  the  serous  membranes 
readily  accessible,  and  the  digestive  tract.  The 


64  HOG   CHOLEKA 

changes  which  appear  in  these  various  parts  have 
already  been  discussed,  so  for  our  present  purpose 
we  will  consider  chiefly  those  which  are  of  primary 
importance  in  their  relation  to  diagnosis. 

The  skin  is  examined  for  ecchymoses  and  yel- 
lowish-brown ulcers  which  sometimes  appear  on 
the  throat  and  other  ventral  surfaces.  If  there 
is  a  purplish  discoloration,  inquiry  should  be  made 
as  to  whether  it  was  noticed  before  death  took 
place.  An  affirmative  reply  suggests  hog  cholera, 
while  a  negative  one  practically  dismisses  the  le- 
sion from  consideration.  Changes  in  the  skin  are 
frequently  absent. 

As  we  open  the  thoracic  and  abdominal  cavi- 
ties petechiae  and  ecchymoses  are  sometimes  ob- 
served in  or  immediately  beneath  the  serous  sur- 
faces thus  exposed.  They  appear  infrequently  in 
the  parietal  pleura  and  parietal  peritoneum  and 
are  somewhat  more  common  in  the  serous  coat  of 
the  intestine,  especially  that  of  the  cecum  and 
colon. 

The  kidney  lesions  are  highly  characteristic  of 
hog  cholera,  and  they  occur  in  nearly  all  cases. 
They  consist  of  petechiae  which  are  distributed  on 
the  surface,  as  well  as  in  the  deeper  structures. 
These  are  dark  red  in  color  and  sharply  defined, 
often  giving  the  organ  the  "turkey  egg"  appear- 
ance. Sometimes  they  are  so  few  in  number  that 
the  capsule  must  be  removed  in  order  to  see  them, 


DIAGNOSIS,   DIFFEBENTIAL  DIAGNOSIS,   PEOGNOSIS         65 

care  being  taken  to  make  the  examination  in  a 
strong  light.  Infrequently  other  causes  produce 
peteehias  in  the  kidneys  of  swine,  but  in  this  coun- 
try, unless  another  cause  is  apparent,  either  by 
virtue  of  the  history  or  accessory  lesions,  we  are 
safe  in  attributing  them  to  hog  cholera. 

Petechiae  in  the  mucosa  of  the  bladder  occur  in 
most  cases  of  hog  cholera,  and  they  do  not  often 
result  from  other  causes.  The  serous  surface  is 
practically  always  normal. 

Some  of  the  lymph  glands  are  usually  involved, 
and  to  the  experienced  observer  the  changes  in 
them  aid  greatly  in  making  a  diagnosis.  On  the 
surface  the  gland  is  very  dark  red,  almost  black. 
On  section  the  periphery  is  similar  in  color,  while 
the  deeper  structures  may  remain  unchanged.  It 
is  important  to  bear  in  mind  that  any  inflamma- 
tory process  may  affect  adjacent  lymph  nodes,  and 
to  make  allowance  for  this  fact,  but  marked  per- 
ipheral congestion  or  hemorrhage,  when  observed 
in  several  glands  widely  separated,  in  the  absence 
of  apparent  inflammation  in  adjacent  structures, 
strongly  indicates  hog  cholera. 

The  spleen  reveals  characteristic  hog  cholera  le- 
sions only  in  the  dark,  swollen  circumscribed  hem- 
orrhages, usually  less  than  1  centimeter  in  diam- 
eter, which  appear  along  the  border.  In  field 
cases  that  have  died  of  hog  cholera  these  lesions 
are  not  often  observed,  because  secondary  invad- 


66  HOG    CHOLERA 

ers  have  so  enlarged  and  darkened  the  entire  or- 
gan as  to  render  them  invisible,  and  because  post- 
mortem changes  take  place  rapidly.  The  enlarged, 
dark,  pulpy  spleen  which  is  often  encountered  in 
hog  cholera  outbreaks  is  of  little  significance  in 
diagnosis,  because  it  is  so  frequently  the  result  of 
other  causes. 

The  heart  reveals  no  macroscopic  lesions  in  the 
vast  majority  of  cases,  but  the  petechiae  which  are 
sometimes  visible  on  the  left  auricle,  less  fre- 
quently on  the  right,  and  rarely  involve  the  ven- 
tricles, are  usually  caused  by  hog  cholera  virus. 

The  lungs  are  often  normal.  If  the  surfaces  are 
dotted  with  ecchymoses,  the  fact  suggests  hog 
cholera  quite  strongly,  but  occasionally  these  le- 
sions are  due  to  other  causes. 

The  laryngeal  mucosa  is  often  the  seat  of  pete- 
chiae, which  are  characteristic  of  hog  cholera. 

Examination  of  the  intestinal  mucosa  often  aids 
in  making  a  diagnosis,  but  the  lesions  encountered 
are  often  difficult  to  interpret.  Certain  irritants 
cause  changes  which  may  be  confused  with  those 
due  to  hog  cholera,  and  secondary  invasion  tends 
rapidly  to  modify  filterable  virus  lesions  so  that 
they  are  difficult  to  identify.  Ecchymoses  and 
larger  hemorrhages,  as  well  as  ulcers  of  recent 
origin,  when  distributed  near  the  ileocecal  valve 
and  elsewhere  in  the  mucosa  of  the  caecum  and 
upper  colon,  may  be  accepted  as  supplementary 


DIAGNOSIS,   DIFFEBENTIAL  DIAGNOSIS,   PKOGNOSIS         67 

evidence  of  acute  hog  cholera.  The  "button 
ulcer"  is  usually  associated  with  the  chronic  form, 
but  agents  other  than  the  filterable  virus  may  be 
instrumental  in  producing  it. 

All  these  hog  cholera  lesions  will  not  often  be 
found  in  one  animal,  but  if  two  or  more  organs 
are  involved  this  fact,  supported  by  a  history 
that  does  not  positively  deny  the  presence  of 
the  disease,  may  be  accepted  as  ground  for  a 
diagnosis.  If  more  organs  are  involved  the  evi- 
dence is  more  conclusive. 

AnimaJ  inoculation.  This  method  is  rarely 
applicable  in  actual  practice,  because  it  is  expen- 
sive and  requires  too  much  time.  In  very  excep- 
tional outbreaks  which  present  atypical  features, 
and  in  cases,  involving  litigation  it  may  be  useful. 
The  essentials -of  a  conclusive  experiment  may  be 
sunrniarized"  thus :. 

1.  Blood  should  be  drawn  from  a  hog  which  has 
been  sick  for  only  a  short  time,  and  which  carries 
a  temperature  near  106°  F. 

2.  The  .  blood  -should  be   diluted   with   sterile 
water  and  passed  through  a  filter  which  retains 
all  microscopic  organisms. 

3.  Enough  of  the  filtrate  to  represent  at  least 
1  mil  of  the  undiluted  blood  should  be  injected 
into  a  susceptible  pig,  preferably  one  weighing 
between  forty  and  one  hundred  pounds. 

4.  Twelve  days  previous  and  subsequent  to  the 


68  HOG   CHOLERA 

date  of  injection  the  pig  should  be  protected  from 
extraneous  hog  cholera  infection;  all  receptacles 
and  instruments  used  in  making  the  injections 
should  be  sterilized. 

5.  Symptoms  of  hog  cholera  should  appear  in 
less  than  eight  days  following  the  injection. 

6.  The  pig  should  die  in  less  than  seven  days 
following  the  appearance  of  symptoms,  or  at  the 
end  of  that  time,  providing  it  is  still  sick,  it  should 
be  killed. 

7.  Autopsy  should  reveal  typical  hog  cholera 
lesions  in  at  least  two  organs. 

8.  In  negative  experiments  the  susceptibility  of 
the  experimental  pig  should  be  proved  by  a  subse- 
quent injection  with  at  least  1  mil  of  virulent  hog 
cholera  blood. 

Differential  Diagnosis 

Peculiar  difficulties  are  met  in  the  differential 
diagnosis.  Clinical  examination  of  the  individ- 
ual is  subject  to  limitations  which  are  not  encoun- 
tered in  dealing  with  larger  animals,  and  some  of 
the  maladies  which  we  seek  to  differentiate  from 
hog  cholera  occur  so  frequently  in  combination 
with  that  disease  that  we  do  not  always  have  well 
defined  features  upon  which  to  base  our  conclu- 
sions. Thus  under  certain  circumstances  we  have 
not  only  to  decide  whether  a  given  outbreak  is 
hog  cholera  or  swine  plague,  but  we  must  also 


DIAGNOSIS,    DIFFEKENTIAL   DIAGNOSIS,    PROGNOSIS         69 

ask  ourselves  whether  the  two  diseases  exist  in 
combination.  Laboratory  examinations  may  dem- 
onstrate the  presence  of  a  bipolar  organism,  but 
they  cannot  in  the  course  of  a  few  hours  deny  the 
presence  of  the  hog  cholera  virus,  and  thus  they 
are  often  dangerously  misleading.  Return  mail 
diagnoses  of  " swine  plague"  or  "hemorrhagic 
septicemia"  are  without  value  because  they  ignore 
consideration  of  hog  cholera  virus,  which  in  this 
country  is  present  in  most  outbreaks  of  rapidly 
transmissible  swine  disease. 

Among  the  diseases  from  which  hog  cholera 
must  be  differentiated  are  uncomplicated  swine 
plague,  pneumonias  due  to  a  variety  of  causes,  sep- 
ticemias,  tuberculosis,  anthrax,  so-called  "flu," 
various  parasitisms,  soap  poisoning,  brine  poison- 
ing, and  sudden  deaths  from  such  causes  as  heat- 
stroke and  lightning-stroke.  Eouget  and  rinder- 
pest are  also  to  be  considered  in  countries  in  which 
they  are  prevalent. 

The  differential  diagnosis  cannot  be  made  by 
rule  of  thumb,  nor  is  it  possible  to  summarize 
or  tabulate  the  determining  features  of  these  va- 
rious maladies,  so  that  the  inexperienced  observer 
can  distinguish  among  them.  Armed  with  defi- 
nite knowledge  of  the  diseases  with  which  he  is 
dealing  the  diagnostician  usually  reaches  his  con- 
clusions rapidly  and  accurately.  In  the  absence 
of  such  knowledge,  a  few  rules  do  not  suffice. 


70  HOG   CHOLERA 

Having  already  dealt  with  the  distinguishing  fea- 
tures of  hog  cholera  we  will  confine  our  remarks 
chiefly  to  characteristics  which  suggest  the  pres- 
ence of  these  other  diseases. 

Swine  plague.  Swine  plague  rarely  occurs  in 
pure  form,  it  affects  only  a  portion  of  the  animals 
in  a  herd,  and  there  are  frequent  spontaneous  re- 
coveries. There  is  often  a  history  of  recent  ship- 
ping. The  incubation  period  is  short  (1  to  3  days), 
acute  dyspnea  and  thumping  are  prominent  symp- 
toms, and  the  hogs  show  more  distress  than  is 
observed  in  hog  cholera  attacks.  High  tempera- 
tures are  not  the  rule  except  during  the  first  few 
hours  of  sickness.  The  characteristic  "  swine 
plague  pneumonia, "  if  present  in  several  autop- 
sies, speaks  for  the  existence  of  swine  plague,  but 
the  absence  of  the  filterable  hog  cholera  virus 
must  be  clearly  established  before  a  diagnosis  of 
pure  swine  plague  is  justified. 

None  of  the  pneumonias,  with  the  exception  of 
that  associated  with  swine  plague,  are  accom- 
panied by  the  lesions  in  other  organs  which  char- 
acterize hog  cholera.  Usually  they  occur  where 
pigs  are  kept  in  very  dusty  quarters,  or  where 
the  floors  are  cold  and  damp  and  no  dry  litter  is 
provided.  Eecent  shipping  is  a  predisposing  fac- 
tor, and  lung  worm  and  ascarid  infestations  play 
an  important  part  in  their  development.  They 
are  sporadic  or  only  slowly  transmissible.  High 


DIAGNOSIS,   DIFFERENTIAL   DIAGNOSIS,   PROGNOSIS         71 

temperatures  are  not  common,  and  the  prominent 
symptoms  grow  out  of  the  pneumonia  itself. 

Exceptionally  septicemia  due  to  nonspecific  or- 
ganisms may  occur,  but  its  features  are  not  well 
defined.  In  differentiating  we  must  therefore  de- 
pend on  the  more  definite  manifestations  of  hog 
cholera. 

Tuberculosis  may  only  rarely  be  confused  with 
chronic  hog  cholera.  Hogs  following  tuberculous 
cattle  and  those  fed  infected  creamery  by-prod- 
ucts are  most  commonly  affected.  The  history  of 
the  case  should  be  considered  and  if  doubt  remains 
the  intradermal  tuberculin  test  may  be  applied. 
If  material  for  autopsies  is  available,  the  differ- 
entiation presents  no  great  difficulties. 

Anthrax  and  the  peracute  form  of  hog  cholera 
are  not  always  easy  to  differentiate.  If  the  for- 
mer disease  has  existed  previously  in  the  locality ; 
if  other  classes  of  live  stock  are  affected;  if  the 
hogs  show  swelling  of  the  throat  or  froth  mixed 
with  blood  coming  from  the  mouth  or  nostrils ;  if 
the  blood  is  black  and  incoagulable,  anthrax  should 
be  suspected,  and  a  microscopical  examination 
made. 

A  malady  known  as  * 'state  fair  disease* '  or 
"flu"  has  in  recent  years  been  recognized  in  the 
central  states.    It  is  often  associated  with  a  his- 
tory of  recent  shipping,  respiratory  symptoms 
and  lesions  predominate,  and  recovery  is  the  rule. 


72  HOG   CHOLERA 

This  latter  fact  alone  will  distinguish  it  from  hog 
cholera,  when  it  occurs  in  pure  form. 

Ascaris  infestation  and  hog  cholera  sometimes 
exist  in  the  same  herd.  As  a  result  of  the  diar- 
rhea incident  to  the  latter  disease  ascarids  are 
frequently  evacuated  in  the  feces,  and  the  entire 
train  of  symptoms,  as  well  as  the  deaths,  is  attrib- 
uted to  the  parasites  alone.  Even  though  the 
parasites  are  present  in  large  numbers,  if  deaths 
are  numerous,  further  examination  should  be 
made  for  evidence  of  hog  cholera. 

Lung  worms  cause  cough,  emaciation  and  other 
symptoms  which  resemble  those  observed  in 
chronic  hog  cholera.  The  history  of  the  outbreak, 
supplemented  if  necessary  by  an  autopsy,  will  be 
sufficient  to  determine  its  cause.  Chronic  hog 
cholera  is  usually  a  sequel  of  the  acute  form. 
Lung  worms  are  often  associated  with  pneumonia, 
causing  death  most  frequently  in  young  pigs. 
Unless  great  care  is  used  these  parasites  may  be 
overlooked.  The  smaller  air  passages  should  be 
laid  open  with  sharp  shears  and  the  examination 
made  in  a  strong  light. 

Considered  collectively,  the  various  drug  and 
food  poisonings  differ  from  hog  cholera  in  that 
several  animals  often  are  affected  at  the  same 
time,  the  symptoms  as  a  rule  are  more  violent, 
vomiting  is  more  common,  and  temperatures  are 
not  so  high.  The  history  may  reveal  the  source 


DIAGNOSIS,   DIFFERENTIAL   DIAGNOSIS,    PROGNOSIS         73 

of  the  particular  poison,  and  some  of  the  drug 
poisonings  (strychnin,  belladonna,  lead)  are  in 
themselves  characteristic.  Poisoning  with  the  al- 
kaloids produces  no  lesions,  and  no  poison,  so  far 
as  we  know,  is  responsible  for  changes  which  are 
observed  in  hog  cholera.  Common  salt  (sodium 
chlorid)  is  especially  poisonous  for  hogs  that  are 
not  accustomed  to  it,  causing  intense  inflammatory 
changes  in  the  digestive  mucosa,  and  congestion 
of  the  meninges.  Long  continued  feeding  with 
material  containing  soap  and  lye  will  produce 
disease  resembling  chronic  hog  cholera.  How- 
ever, our  task  is  usually  to  differentiate  between 
poisonings  and  acute  hog  cholera,  and  this  pre- 
sents no  great  difficulties  if  we  resort  to  autopsies, 
for  none  of  the  poisons  produce  lesions  which  re- 
semble those  observed  in  acute  hog  cholera. 

In  suspected  heat-stroke  and  lightning-stroke, 
the  history  is  an  important  guide.  Heat-stroke 
occurs  most  frequently  in  fat  hogs  deprived  of 
shade  or  water  in  hot  weather,  and  in  those 
shipped  in  overcrowded  stock  cars,  or  subjected 
to  excitement  or  violent  exertion  during  the  sum- 
mer months.  The  hair  of  hogs  dead  of  lightning- 
stroke  may  be  seared,  there  may  be  arborescent 
congestion  or  hemorrhage  in  and  beneath  the  skin 
at  the  point  where  the  current  entered  the  body, 
and  sometimes  there  are  lacerations  of  the  inter- 
nal organs.  Eigor  mortis  is  not  pronounced. 


74  HOG   CHOLERA 

Rouget  or  swine  erysipelas  does  not  exist  in 
the  United  States.  The  septicemic  form  of  the 
disease  resembles  hog  cholera  very  closely.  It 
has  a  shorter  incubation  period  than  the  latter 
disease,  but  resort  must  often  made  to  microscop- 
ical examination,  in  order  to  distinguish  between 
them. 

Rinderpest  does  not  occur  in  the  United  States, 
and  in  countries  in  which  it  is  prevalent,  swine  do 
not  contract  it  readily.  For  this  reason  it  is  not 
well  characterized,  but  in  case  of  necessity  it  may 
be  distinguished  from  hog  cholera  by  nitration 
experiments  in  which  cattle  are  used  as  test  ani- 
mals. Both  viruses  are  filterable,  but  that  of 
rinderpest  is  the  only  of  the  two  which  affects 
bovines. 

Prognosis 

In  the  individual,  hog  cholera  runs  a  rapid  and 
fatal  course,  and  even  when  recoveries  occur,  they 
may  be  slow  and  incomplete.  Therefore  in  all 
hogs  visibly  sick  the  prognosis  is  bad,  but  it  is  the 
herd  as  a  unit  which  we  must  consider,  for  we  are 
frequently  called  on  to  estimate  the  salvage  which 
may  be  expected.  The  ability  to  do  this  with  a 
reasonable  degree  of  accuracy  is  acquired  only  by 
experience,  and  it  is  a  great  asset  to  one  who  han- 
dles hog  cholera  in  the  field.  We  can  indicate  -only 
the  guiding  principles  upon  which  the  progno- 
sis depends. 


75 

The  number  of  animals  dead  and  visibly  sick 
at  the  time  of  serum  treatment  forms  our  chief 
basis  of  estimate.  Assuming  that  a  herd  is  kept 
under  average  farm  conditions,  and  that  there  is 
no  evidence  of  complications,  as  a  very  general 
rule  we  expect  to  save  about  as  many  hogs  as  are 
eating  greedily  and  are  free  from  abnormal  tem- 
peratures on  the  date  of  serum  administration. 
Some  of  those  that  show  no  fever  will  die,  and  a 
few  of  those  that  show  fever  will  recover,  one 
class  approximately  compensating  the  other. 

In  herds  in  which  it  is  not  possible  to  secure 
reliable  temperature  readings,  the  prognosis  must 
be  more  guarded.  In  general,  during  the  early 
days  of  an  outbreak,  we  expect  about  as  many 
deaths  to  follow  serum  treatment  as  the  combined 
sum  of  the  hogs  that  have  previously  died  and 
those  visibly  sick  when  serum  is  administered. 
If  fifty  per  cent  of  the  animals  in  a  herd  are  dead 
or  visibly  sick  we  expect  the  salvage  to  offset  the 
cost  of  serum  treatment,  and  leave  something  to 
spare,  but  we  cannot  promise  much  in  such  a  herd. 

Evidence  of  secondary  infection,  coexisting  par- 
asitisms, improper  feeding  and  housing,  a  history 
of  recent  shipping  or  other  weakening  influences 
all  call  for  a  guarded  prognosis.  If  the  hogs  have 
not  been  confined  closely,  or  if  they  are  in  several 
pens  some  of  which  remain  uninfected,  the  prog- 
nosis is  relatively  more  favorable. 


CHAPTER  VII 

PREPARATION  OF  ANTI-HOG-CHOLERA  SERUM  AND  HOG 
CHOLERA   VIRUS 

WE  are  indebted  to  Dr.  Marion  Dorset  and  Dr. 
W.  B.  Niles  of  the  United  States  Bureau  of  Ani- 
mal Industry  for  developing  our  present  method 
of  preparing  anti-hog-cholera  serum.  The  dis- 
covery that  hog  cholera  is  caused  by  a  filterable 
virus  dismissed  further  efforts  to  immunize 
against  it  with  products  of  various  bacteria,  but 
it  suggested  hope  for  a  protective  serum  analo- 
gous to  that  used  against  rinderpest,  a  filterable 
virus  disease  of  cattle.  That  hope  was  realized 
in  1908  when  Dorset  announced  his  discovery,  and 
although  the  immediate  control  of  hog  cholera 
which  some  predicted  did  not  materialize,  the  ob- 
stacles encountered  have  not  been  due  to  any  fun- 
damental defect  in  the  serum  itself.  When  prop- 
erly prepared  and  used  it  is  one  of  the  most  effec- 
tive biologies  known  to  preventive  medicine. 

Anti-hog-cholera  serum  production  is  highly  or- 
ganized and  carefully  controlled  in  the  United 
States  and  many  laboratories  are  in  operation 
which  are  models  for  convenience,  cleanliness  and 

76 


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77 


78  HOG    CHOLEKA 

sanitation.  All  laboratories  which  make  inter- 
state shipments  must  secure  licenses  from  the  fed- 
eral government  and  submit  to  regulations  which 
have  been  formulated  to  protect  those  who  use 
the  products.  The  laboratories  must  meet  certain 
well-defined  requirements  before  they  are  allowed 
to  operate,  and  thus  despite  great  deviation  in  de- 
tail, the  same  fundamental  processes  are  used  in 
all  of  them.  We  will  consider  first  the  essential 
requirements  for  preparing  the  protective  defib- 
rinated  blood,  which  has  been  called  anti-hog-chol- 
era serum,  and  which  forms  the  basis  of  all  the 
more  or  less  refined  products  used  to  prevent  hog 
cholera  in  the  field. 

Buildings.  The  buildings  should  be  suited  to 
the  conditions  under  which  the  laboratory  is  to 
operate.  These  conditions  vary  so  widely  that 
uniformity  is  neither  to  be  expected  nor  desired, 
but  certain  governing  principles  should  be  ob- 
served in  all  construction.  In  general,  simplicity, 
convenience  in  operation,  and  provisions  for  clean- 
liness are  the  primary  considerations.  Future  up- 
keep costs  should  also  be  reduced  to  a  minimum 
in  the  original  construction.  Under  most  condi- 
tions concrete  is  the  best  material  to  use. 

The  walls,  ceiling  and  floors  should  be  fin- 
ished so  that  water  will  not  injure  them.  The 
floors  should  be  drained  in  a  sanitary  manner. 
Steam  or  hot  water  heat  should  be  provided,  the 


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79 


80  HOG    CHOLERA 

building  should  be  plumbed  for  hot  and  cold 
water,  and  all  outside  doors  should  be  screened  in 
summer.  Ample  light  and  ventilation  are  re- 
quired. 

The  minimum  requirements  for  reasonable  con- 
venience and  cleanliness  in  a  serum  laboratory 
consist  of  preparation  room,  bleeding  room,  serum 
laboratory  proper,  office,  dressing  room  and  lava- 
tories, store  room  and  refrigerator  room,  as  well 
as  furnace  room  and  coal  bins  so  situated  that 
dust  from  them  will  not  contaminate  other  parts 
of  the  building. 

Quarters  for  the  hogs  should  be  suited  to  local 
requirements.  In  any  event  they  should  be  at 
least  seventy-five  feet  from  the  laboratory  build- 
ing, and  even  a  greater  distance  is  desirable. 
The  floors  should  be  of  concrete,  well  drained, 
and  ample  light  and  ventilation  should  be  pro- 
vided. Boom  for  exercise  on  the  ground  is  desir- 
able, and  pasture  for  hogs  that  are  to  be  kept 
for  several  weeks  is  a  great  asset.  Provision 
should  be  made  for  sanitary  disposal  of  manure, 
and  other  waste  from  the  laboratory  and  hog 
quarters.  In  general,  convenience  for  those  who 
care  for  the  animals,  and  cleanliness  and  comfort 
for  the  animals  themselves  are  the  chief  consid- 
erations. 

The  equipment  of  the  laboratory  is  likewise 
governed  by  individual  needs.  Too  much  equip- 


PBEPAEATION    OF   ANTI-HOG-CHOLEKA   SERUM         81 

ment  is  a  detriment,  as  methods  are  constantly 
changing  and  improving  and  each  unnecessary  fix- 
ture takes  up  room  and  must  be  kept  clean.  Es- 
sential major  equipment  includes  facilities  for 
washing,  sterilizing  and  storing  all  instruments 
and  containers  used,  vacuum  and  pressure  tanks 
connected  with  motor  driven  pumps,  portable 
crates  for  tail  bleeding  and  hypering,  portable  or 
stationary  tables  or  stocks  for  bleeding  serum  hogs 
and  virus  pigs  from  the  throat,  scales,v  motor 
driven  shaker,  serum  mixer  and  office  equipment 
including  forms  for  keeping  records. 

Minor  equipment  includes  bleeding  and  hyper- 
ing  units,  tail  shears,  clamps,  hypodermic  syringes 
and  needles,  wax  heater,  cannulas  and  sticking 
knives,  scalpels,  instrument  trays,  antiseptic  con- 
tainers, funnels,  graduates,  pipettes,  defibrinating 
forks,  porcelain  containers  for  serum  and  virus 
blood,  apparatus  for  separating  out  fibrin  and  clot, 
and  bottles  for  storing  and  shipping. 

Grouped  around  this  essential  unit  may  be  a 
multitude  of  accessories,  or  the  unit  itself  may  be 
multiplied  so  as  to  provide  for  production  on  a 
large  scale.  Facilities  for  butchering,  for  cooling 
carcasses,  for  rendering  virus  pig  carcasses,  for 
handling  virus  in  separate  rooms,  for  keeping 
susceptible  pigs  isolated,  for  dipping  and  isolating 
new  arrivals,  for  bacteriological  work,  for  packing 
and  mailing  products,  and  for  exposing  serum  and 


82  HOG    CHOLEEA 

virus  pigs  to  calves  so  as  to  guard  against  foot- 
and-mouth  disease,  are  just  a  few  of  the  acces- 
sories that  circumstance  must  include  or  elimin- 
ate. 

Further  detail  in  regard  to  equipment  cannot  be 
profitably  discussed  here.  In  all  these  things  sim- 
plicity, cleanliness,  convenience  and  low  upkeep 
cost  are  the  chief  considerations.  Good  equip- 
ment invites  clean  operations,  but  in  the  last  anal- 
ysis the  quality  of  the  finished  product  is  not  de- 
termined by  equipment.  A  careless  operator  will 
contaminate  serum  in  spite  of  every  convenience ; 
a  careful  one  will  produce  clean  products  under 
adverse  working  conditions. 

'Principle  governing  serum  production.  When 
a  hog  contracts  cholera  and  recovers,  or  when  it 
receives  simultaneously  hog  cholera  virus  and 
protective  serum,  it  is  thereafter  immune  to  the 
disease.  The  body  cells,  in  self-defense,  have  elab- 
orated substances,  termed  antibodies,  which  neu- 
tralize the  effects  of  all  hog  cholera  virus  subse- 
quently introduced  into  the  system.  In  the  ordi- 
nary immune  hog  these  antibodies  protect  against 
any  quantity  of  cholera  virus  to  which  the  animal 
may  be  exposed,  but  they  do  not  exist  in  sufficient 
concentration  so  that  the  blood  may  be  used  to 
protect  other  animals.  Antibody  elaboration 
must  be  further  stimulated,  and  this  is  done  by 
giving  the  immune  an  enormous  intravenous  dose 


PREPARATION    OF   ANTI-HOG-CHOLERA   SERUM          83 

of  virulent  hog  cholera  blood.  A  slight  reaction 
follows,  and  in  the  course  of  a  few  days  the  im- 
mune becomes  a  hyperimmune  and  comparatively 
small  doses  of  its  blood  will  protect  other  hogs  ex- 
posed to  cholera. 

We  are  now  ready  to  consider  in  some  detail  the 
various  steps  required  in  preparing  anti-hog-chol- 
era serum.  In  all  these  it  is  a  principle  that  the 
operating  room  shall  be  clean  and  free  from  dust, 
that  the  floor  shall  be  dampened,  that  the  operator 
shall  wear  clean  clothing  and  that  his  hands  shall 
be  scrupulously  clean.  The  hands  must  not  touch 
the  serum  or  virus  blood,  and  all  instruments  and 
containers  with  which  the  blood  comes  in  contact 
must  be  sterilized  before  use.  Antiseptic  solution 
should  be  applied  by  means  of  a  gravity  irrigator 
or  some  other  device  which  prevents  the  hands 
from  passing  alternately  between  operating  field 
and  antiseptic  container.  Exact  records  of  each 
operation  must  be  kept,  and  each  hog  used  must 
be  identified  with  a  number  tag. 

Immunizing.  Requirements.  Two  hypodermic 
syringes,  one  ten  mil  capacity  or  less,  for  virus, 
the  other  twenty  mil  capacity  or  more,  for  serum ; 
scrub-brush  and  antiseptic  solution,  also  anti-hog- 
cholera  serum  and  hog  cholera  virus  each  in  a 
separate,  covered  receptacle. 

The  pig  is  held  by  an  assistant  and  the  skin 
covering  both  armpits  (or  the  inner  region  of  both 


84  HOG    CHOLEKA 

hams)  is  thoroughly  scrubbed  with  antiseptic  so- 
lution. Then  two  mils  of  virus  are  injected  into 
one  armpit,  and  the  required  quantity  of  serum 
(about  35  mils  for  a  100  pound  pig)  is  injected 
into  the  other.  Deep  injections  are  desirable. 

Following  this  treatment  the  pig  undergoes  a 
reaction  beginning  in  about  five  days  and  lasting 
about  a  week,  during  which  time  a  permanent  im- 
munity to  hog  cholera  is  established.  It  is  de- 
sirable to  immunize  prospective  hypers  as  com- 
paratively young  shoats  and  to  delay  hypering 
until  they  have  attained  a  weight  of  at  least  two 
hundred  pounds,  as  a  long  interval  between  the 
date  of  immunizing  and  that  of  hypering  favors 
potent  serum.  In  no  instance  should  this  interval 
be  less  than  sixty  days. 

The  Virus  Pig 

In  order  that  the  immune  may  receive  addi- 
tional virus  and  become  a  hyper,  a  supply  of  virus 
must  be  procured.  This  is  done  by  injecting  sus- 
ceptible shoats  with  lethal  doses  of  hog  cholera 
virus  and  collecting  their  blood  after  they  sicken 
with  the  disease.  A  virus  pig  should  be  in  thrifty 
condition,  weighing  near  one  hundred  pounds.  It 
should  not  be  heavily  infested  with  parasites. 
The  dose  of  virus  (about  2  mils)  is  injected  in  the 
same  manner  as  has  already  been  described,  but 
no  protective  serum  is  given. 


PEEPAEATION    OF    ANTI-HOG-CHOLERA   SEBUM          85 

Four  or  five  days  subsequent  to  injection  the 
pig  should  show  a  temperature  near  106°  F.,  and 
a  day  or  two  later  marked  symptoms  of  hog  chol- 
era should  appear.  As  a  very  general  guide  it 
may  be  said  that  a  virus  pig  is  ready  to  bleed  when 
it  has  carried  a  high  temperature  for  about  three 
days  and  when  it  has  shown  severe  symptoms  of 
hog  cholera  for  about  two  days.  A  good  strain  of 
virus  will  bring  this  about  in  approximately  seven 
days  subsequent  to  the  date  of  injection.  The 
time  required  may  be  extended  in  certain  individ- 
uals, but  a  virus  that  regularly  requires  more  than 
eight  days  in  which  to  ' '  ripen ' J  pigs  for  bleeding 
is  not  desirable  for  hypering. 

Bleeding  the  virus  pig.  When  the  sick  pig  is 
ready  to  bleed  for  virus  it  is  taken  to  the  labora- 
tory. In  the  preparation  room  the  entire  body 
is  washed,  and  the  animal  is  secured  to  a  tilting 
operating  table,  revolving  door  or  other  device  for 
securing  it  by  the  hind  legs  and  suspending  it 
head  downward.  The  front  legs  are  secured  well 
apart  and  the  snout  tied  backward,  stretching  the 
skin  covering  the  throat.  The  throat  and  sternal 
region  are  then  thoroughly  lathered  (an  antiseptic 
soap  is  desirable),  carefully  shaved  and  rinsed, 
and  an  antiseptic  solution  is  applied.  If  it  is  a 
male  pig  a  clamp  is  attached  to  the  prepuce  to 
prevent  dribbling  of  urine.  Finally  the  entire 
body  is  covered  with  a  cloth,  previously  dampened 


86  HOG   CHOLERA 

in  antiseptic  solution,  leaving  only  the  throat  ex- 
posed, and  all  is  ready  to  draw  the  blood. 

An  ordinary  two-quart  fruit  jar,  previously 
sterilized,  is  a  good  receptacle.  The  sticking  may 
be  done  with  a  large  cannula  designed  especially 
for  the  purpose,  or  with  a  narrow  bladed  knife. 
In  case  a  knife  is  used  the  hand  should  be  held 
low  on  the  throat  so  that  the  blade  passes  directly 
upward,  the  back  against  the  dorsal  surface  of  the 
sternum.  The  blade  should  not  leave  the  median 
line,  but  should  be  forced  upward  until  it  severs  a 
carotid  or  the  anterior  aorta  near  the  bifurcation. 
A  free  clean  incision  made  in  withdrawing  the 
knife  facilitates  rapid  and  complete  bleeding.  A 
pig  weighing  one  hundred  pounds  should  yield 
about  one  thousand  mils  of  blood.  If  pigs  are 
killed  too  late,  after  they  are  very  weak,  the  yield 
is  greatly  reduced. 

Handling  the  virus  blood.  Immediately  after 
the  blood  is  drawn  it  is  defibrinated.  This  is  done 
by  closing  the  receptacle  tightly  and  shaking  it 
vigorously  for  a  few  moments.  It  is  then  marked 
for  identification  and  placed  in  ice- water  pending 
the  time  when  the  pig  that  yielded  the  blood  can 
be  autopsied.  Assuming  that  the  autopsy,  which 
will  be  considered  later,  has  been  satisfactory,  the 
next  step  is  to  separate  out  the  fluid  part  of  the 
blood,  leaving  the  clot  and  fibrin  behind.  This  is 
accomplished  in  various  ways.  Some  use  a  cen- 


PEEPABATION    OF    ANTI-HOG-CHOLERA   SERUM          87 

trifuge  of  which  the  essential  part  is  an  enclosed, 
revolving,  perforated  cylinder;  others  pour  the 
contents  of  the  jars  directly  into  funnels  into 
which  one  or  more  thicknesses  of  sterile  gauze 
have  been  placed ;  still  others  empty  the  jars  into 
perforated  funnels  which  fit  into  the  tops  of  tall  re- 
ceptacles into  which  the  fluid  drains,  and  near  the 
bottom  of  which  is  a  turncock  for  drawing  it  off. 
Formerly  clot  presses  were  used  universally  as  a 
final  means  of  extracting  the  last  drop  of  blood 
from  the  fibrin  and  clot,  but  this  practice  is  gradu- 
ally being  abandoned.  It  increases  the  yield  but 
little,  and  adds  unnecessary  debris  to  the  blood, 
whether  it  is  serum  or  virus.  In  all  methods  of 
handling  the  final  act  is  to  strain  the  blood  through 
gauze,  after  which  it  is  placed  in  storage  bottles 
and  refrigerated  pending  the  time  when  it  is  re- 
quired for  hypering.  The  blood  of  several  virus 
pigs  is  mixed  after  autopsies  have  confirmed  its 
fitness  for  use. 

This  "hypering  virus "  may  be  kept  forty-eight 
hours  or  even  longer,  but  it  is  best  to  use  it  after 
it  has  been  refrigerated  about  one  day.  It  is  well 
to  strain  it  a  second  time  just  before  it  is  to  be  in- 
jected. Preservative  is  never  added  to  hypering 
virus. 

The  autopsy.  The  two  essential  requirements 
for  a  virus  pig  are  that  it  shall  show  complete  evi- 
dence that  it  was  suffering  with  acute  hog  cholera 


88 


HOG    CHOLERA 


at  the  time  it  was  killed,  and  that  it  shall  be  free 
of  other  infectious  diseases  which  may  be  trans- 
mitted through  its  blood.  The  clinical  history  of 
the  pig,  and  more  especially  the  autopsy,  enables 
us  to  select  on  this  basis.  If  in  addition  to  a  clini- 


PLATE  9.  Post-mortem  room  where  autopsies  on  virus  pigs  are 
held.  Each  pig  must  show  marked  lesions  of  acute  hog  cholera, 
and  must  be  free  from  other  infectious  diseases.  (Courtesy 
Pitman-Moore  Biological  Laboratories.) 

cal  history  suggesting  hog  cholera  a  pig  shows 
characteristic  lesions  of  the  disease,  slight  or  se- 
vere, in  two  or  more  organs,  we  consider  the  first 
requirement  satisfied.  Generalized  tuberculosis 
disqualifies,  but  slight  and  localized  tubercular  le- 


PREPARATION   OF   ANTI-HOG-CHOLERA   SERUM         89 

sions  do  not  cause  rejection.  Here,  we  believe,  a 
very  rigid  interpretation  is  advisable,  and  in  all 
cases  which  admit  doubt  the  pigs  should  be  re- 
jected. 

Pigs  that  show  enormously  enlarged,  dark, 
pulpy  spleens  as  well  as  those  that  bleed  scantily 
and  yield  very  dark  blood  do  not  produce  satisfac- 
tory virus.  The  tendency  in  both  cases  is  for  the 
blood  to  defibrinate  imperfectly  and  when  it  is 
mixed  with  good  virus  the  entire  lot  may  be 
ruined. 

In  the  routine  autopsy  the  skin,  and  all  of  the 
thoracic  and  abdominal  viscera  are  examined,  as 
well  as  the  submaxillary  and  superficial  inguinal 
lymph  glands.  In  case  of  doubt,  due  to  slight  le- 
sions, the  mucosa  of  the  larynx  and  popliteal 
lymph  nodes  should  be  included. 

Disposal  of  carcass.  Virus  pig  carcasses  may 
be  burned  or  rendered  as  circumstances  direct. 

The  Hyperimmune 

The  immunes  which  are  to  be  hyperimmunized 
and  later  yield  serum  should  be  carefully  selected. 
The  longer  they  have  been  immune  to  hog  cholera, 
the  better.  They  should  be  hearty  feeders,  in 
moderate  flesh,  and  always  strong  and  active. 
The  ears  should  be  moderately  large,  but  thin  and 
well  veined,  and  the  tail  at  least  of  average  length 
so  as  to  permit  the  required  number  of  bleedings. 


90  HOG   CHOLEKA 

A  weight  near  two  hundred  pounds  is  desirable. 
The  intradermal  tuberculin  test  should  be  applied 
to  prospective  hypers,  and  all  reactors  rejected. 

Hypering.  The  immune  is  confined  in  a  port- 
able crate  and  the  snout  is  secured  firmly,  drawing 
the  head  to  one  side.  Its  weight  is  then  obtained 
and  recorded,  and  it  is  wheeled  to  the  preparation 
room  in  the  laboratory.  The  entire  body  is  wet 
thoroughly  and  a  cloth  dampened  in  antiseptic  so- 
lution is  thrown  over  it,  leaving  only  the  head  ex- 
posed. One  of  the  ears  is  lathered,  shaved,  rinsed 
and  washed  in  antiseptic  solution  and  the  hog, 
thus  prepared,  is  wheeled  to  the  hypering  room  to 
receive  the  required  dose  of  virus. 

The  hypering  operation  consists  of  injecting 
into  an  ear  vein  five  mils  of  virus  blood  for  each 
pound  the  hog  weighs.  The  virus  is  placed  in  a 
graduated  bottle  which  is  closed  with  a  rubber 
stopper,  perforated  in  two  places.  Through  one 
opening  is  passed  a  curved  nickeled  tube  which,  ex- 
tending to  the  bottom  of  the  bottle,  serves  as  an 
outlet  for  the  virus  when  air  pressure  is  applied ; 
through  the  other  is  passed  a  shorter  tube  extend- 
ing just  through  the  stopper  and  through  which 
air  is  pumped  to  produce  pressure.  Both  are  ex- 
tended with  rubber  tubing,  the  intake  being  thus 
connected  with  a  tank  containing  compressed  air, 
and  the  outlet  terminating  in  a  slip  fitting  for  the 
hypodermic  needle  which  is  to  be  introduced  into 


PEEPAEATION    OF    ANTI-HOG-CHOLEKA    SERUM          91 

the  ear  vein.  On  this  outlet  tube  is  a  pinch-cock 
to  control  the  flow  of  virus.  The  bottle  is  filled 
with  virus,  the  stopper  is  forced  down  tightly  with 


PLATE  10.  A  close  view  showing  the  hypering  process. 
A  200  pound  cholera  immune  hog  receives  1000  mils 
of  virus  in  the  ear  vein.  In  ten  days  the  animal  is 
ready  to  bleed  for  protective  serum.  New  York  State 
Veterinary  College  at  Cornell  University 


92  HOG    CHOLERA 

a  screw  clamp,  enough  virus  is  passed  through  the 
system  to  eliminate  danger  from  air  bubbles,  the 
pinch-cock  is  closed,  and  all  is  ready  to  make  the 
injection. 

The  vein  into  which  the  needle  must  be  intro- 
duced usually  conforms  roughly  to  the  contour 
of  the  outer  margin  of  the  ear,  and  is  about  one 
inch  removed  from  it.  A  spring  clamp  is  ap- 
plied near  the  base  of  the  ear,  thus  compressing 
this  vein  and  rendering  it  plainly  visible.  The 
ear  is  drawn  taut  with  the  left  hand,  and  with 
the  right  the  needle  is  thrust  quickly  into  the  vein, 
passed  rapidly  along  its  course  about  two  inches, 
and  secured  in  position  with  the  clamp  which  is 
no  longer  needed  to  compress  the  vein  at  the  base 
of  the  ear.  If  the  needle  is  properly  in  place  there 
will  be  a  backward  flow  of  blood  through  it.  With- 
out a  moment's  delay  it  is  now  necessary  to  con- 
nect the  needle  with  the  supply  of  virus  under 
pressure,  and  to  open  the  pinch-clock  allowing  the 
virus  to  flow  into  the  circulation.  Otherwise  the 
hog's  blood  may  clot  in  the  needle  rendering  the 
injection  impossible.  When  the  flow  of  virus  is 
established,  one  must  see  that  the  needle  is  re- 
tained in  place  until  the  required  quantity,  al- 
ready determined,  has  been  injected.  This  will 
require  from  four  to  thirty  minutes,  the  time  be- 
ing governed  by  the  degree  of  pressure  applied, 
by  the  size  of  the  needle  and  the  accuracy  with 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM         93 

which  it  has  been  placed  in  the  vein,  as  well  as  by 
individual  differences  in  hogs  that  are  not  well 
understood.  When  the  required  quantity  of  virus 
has  been  injected,  the  pinch-cock  is  closed,  the 
needle  is  withdrawn,  and  the  hog  is  wheeled  away 
and  released. 

This  describes  the  hypering  operation  in  its 
simplest  form  with  everything  favoring  the  oper- 
ator. Volumes  could  be  written  about  the  at- 
tempts that  end  in  failure.  Practice  is  important, 
but  a  natural  surgical  touch  amounting  almost  to 
instinct  is  required  of  the  expert  operator,  and 
even  he  may  experience  unexplainable  lapses  in 
the  execution  of  his  technique.  However,  most  of 
the  annoyances  experienced  may  be  overcome,  and 
it  seems  desirable  to  include  a  few  suggestions 
which  may  aid  the  beginner  in  his  work. 

At  first  select  hypers  with  ear  veins  straight 
and  prominent;  later  it  will  be  possible  to  hyper 
practically  all  subjects :  begin  the  operation  soon 
after  the  ear  has  been  shaved ;  otherwise  the  vein 
may  recede  and  be  very  difficult  to  distend  so  that 
the  needle  may  enter  it :  use  a  needle  with  a  per- 
fect point ;  a  dull  one  will  roll  the  vein  under  it : 
Hold  the  ear  out  straight;  otherwise  the  skin  will 
be  relaxed  and  the  vein  will  be  unnecessarily  tor- 
tuous :  after  the  needle  has  entered  the  vein  do  not 
release  it  until  it  is  clamped  firmly  in  position; 
the  nub  may  drop  carrying  the  point  upward  and 


94  HOG   CHOLEEA 

causing  it  to  prick  through  the  wall  so  that  virus 
will  escape  from  the  vein  and  accumulate  in  the 
surrounding  tissues  when  it  is  applied  under  pres- 
sure :  if  the  needle  tends  to  pucker  the  skin  at  the 
point  of  entrance,  dampen  both  needle  and  skin 
(an  atomizer  containing  alcohol  is  convenient  for 
this  purpose).  In  inserting  the  needle  hold  the 
index  finger  of  the  right  hand  well  toward  the 
point,  between  the  ear  and  the  needle;  it  is  im- 
possible to  guide  a  needle  when  it  is  grasped  at 
the  nub  only:  if  when  pressure  is  applied  virus 
is  seen  to  escape  from  the  vein  and  accumulate  in 
the  surrounding  tissues,  release  the  pressure  at 
once ;  otherwise  all  chance  of  entering  the  vein  in 
subsequent  trials  will  be  destroyed. 

Before  inserting  the  needle  some  operators 
connect  it  directly  to  the  rubber  tubing  containing 
the  virus  under  pressure,  thus  obviating  annoy- 
ance incident  to  blood  clotting  in  the  needle  or  to 
accidental  breaks  in  the  slip  connection  due  to 
struggling  on  the  part  of  the  hog.  When  this 
technique  is  employed  one  must  depend  largely  on 
his  sense  of  touch  to  determine  when  the  needle 
is  in  position,  for  backward  flow  of  blood  cannot 
be  observed.  In  case  of  doubt  as  to  whether  the 
needle  has  entered  the  vein,  one  may  compress  the 
tubing  between  the  pinch-cock  and  the  needle,  at 
the  same  time  observing  whether  the  virus  thus 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM         95 

forced  out  follows  the  course  of  the  vein  or  is  dis- 
tributed in  adjacent  tissues. 

Occasionally  one  encounters  a  fleshy-eared  hog 
exhibiting  no  ear  vein  which  is  visible  to  the  naked 
eye  in  ordinary  light.  Subjects  of  this  kind  may 
usually  be  hypered  by  darkening  the  room  and 
holding  an  electric  light  bulb  directly  under  the 
ear.  Small,  deeply  covered  veins  are  thus  ren- 
dered plainly  visible,  and  hypering  is  accom- 
plished with  surprising  ease. 

Bangers  and  accidents  due  to  hypering.  The 
ordinary  immune  hog  will  tolerate,  without  inci- 
dent, intravenous  injection  of  five  mils  of  virus 
per  pound  body  weight.  Usually  there  is  no  evi- 
dence of  pain  or  distress,  and  the  animal  lies 
quietly  while  the  dose  is  being  administered.  In 
exceptional  cases,  however,  sudden  death  occurs. 
It  is  a  curious  fact  that  if  distress  is  to  appear, 
it  becomes  evident  before  the  first  half  of  the  dose 
enters  the  circulation.  Thus  it  is  not  quantity 
alone  that  kills.  Other  factors  may  contribute, 
but  the  principal  one  seems  to  be  failure  of  nerv- 
ous control  over  capillary  contraction.  The 
capillary  walls  fail  to  adjust  themselves  to  the 
increased  pressure,  and  as  a  consequence  distend 
and  rupture.  Usually  the  lungs  alone  bear  evi- 
dence of  this  fact,  as  they  contain  the  first  set  of 
capillaries  through  which  the  foreign  blood  must 


96  HOG    CHOLEKA 

pass,  but  occasionally  the  effect  is  observed  in  the 
skin.  Severe  and  general  congestion,  interspersed 
with  areas  revealing  slight  or  extensive  hemor- 
rhage, are  the  usual  changes  observed  in  the 
lungs. 

Prevention  of  sudden  death  resulting  from  hy- 
pering  is  not  always  possible.  Fatalities  occur 
much  less  frequently  if  the  virus  used  is  first 
thoroughly  cooled.  Even  ordinary  refrigerator 
temperatures  are  not  objectionable.  As  a  second 
precaution  a  close  watch  should  be  kept  on  the  hog 
during  the  process  of  hypering,  though  it  is  not 
always  possible  to  distinguish  between  struggles 
due  to  fright  and  perversity  and  those  due  to 
genuine  distress.  Real  danger  is  marked  by  a 
sudden  inspiratory  gasp  or  rapidly  developing 
dyspnea,  especially  when  these  symptoms  are  ac- 
companied by  violent  struggling  and  nervous 
symptoms  such  as  twitching  of  the  snout  or  eye- 
lids and  protrusion  or  shuttling  of  the  eyeballs. 
If  distress  is  not  severe  the  flow  of  virus  may  be 
checked  momentarily  and  then  allowed  to  con- 
tinue slowly,  but  as  a  rule  it  is  best  to  release  the 
hog  and  take  no  further  chances.  Usually  in  sub- 
sequent trials  these  hogs  will  tolerate  hypering 
without  incident. 

Sometimes  it  is  not  until  the  hog  is  released 
from  the  crate  that  we  observe  symptoms.  Vomit- 
ing occurs  somewhat  frequently  at  this  time  but 


PREPARATION    OF   ANTI-HOG-CHOLERA   SERUM         97 

it  is  of  no  particular  consequence.  Great  prostra- 
tion and  severe  dyspnea  are  the  symptoms  which 
suggest  impending  death,  especially  when  foam 
colored  with  blood  exudes  from  the  mouth  or  nos- 
trils. Hogs  suffering  thus  should  be  kept  cool, 
their  heads  should  be  elevated,  and  they  should 
not  be  subjected  to  unnecessary  handling.  Some 
will  recover  spontaneously.  In  fatal  cases  coma 
and  shallow  breathing  precede  death.  We  have 
tried  hypodermic  doses  of  strychnin  under  such 
conditions,  but  while  temporary  relief  is  afforded 
the  treatment  seems  merely  to  delay  death  rather 
than  to  prevent  it. 

Fatalities  sometimes  occur  when  air  is  pumped 
into  the  vein.  These  may  be  avoided  by  forcing 
the  outlet  tube  completely  to  the  bottom  of  the 
bottle,  and  by  allowing,  previous  to  each  opera- 
tion, a  quantity  of  virus  to  pass  through  the  out- 
let sufficient  to  carry  away  bubbles  that  may  be 
accumulated  in  the  rubber  tube.  Air  in  the  vein 
does  not  always  cause  death,  but  the  risk  is  great, 
and  avoidable. 

Deaths  from  hog  cholera  as  a  result  of  hypering 
are  practically  unknown,  except  in  hogs  that  have 
been  purchased  without  a  clear  history  of  having 
been  properly  immunized. 

During  the  interval  between  the  date  of  hyper- 
ing  and  that  of  the  first  bleeding  for  serum,  about 
ten  days,  careful  observations  of  the  hyper  are 


98  HOG   CHOLEEA 

necessary.  The  points  to  be  determined  are 
whether  the  hog  has  been  vigorous  and  healthy, 
and  whether  this  condition  still  prevails  at  bleed- 
ing time.  Temperature  readings,  clinical  obser- 
vations and  comparative  weights  are  the  sources 
of  information,  each  being  employed  as  circum- 
stances direct.  The  average  hyper  shows  a  mod- 
erate and  transitory  fluctuation  of  temperature 
immediately  following  the  dose  of  virus,  and  he 
may  eat  indifferently  for  a  day  or  two,  but  as  a 
rule  his  appetite  is  unimpaired,  and  he  continues 
to  gain  in  weight  about  a  pound  per  day.  If  a 
hog's  appetite  has  been  greedy  during  the  last 
seven  days  preceding  the  date  of  bleeding ;  if  there 
has  been  no  loss  in  weight  or  outward  evidence  of 
sickness ;  and  if  the  temperature  is  normal  when 
bleeding  time  arrives,  we  consider  the  animal  a 
fit  subject  to  produce  serum. 

Bleeding  for  serum.  The  hog  is  confined  in  a 
portable  crate  and  wheeled  to  the  preparation 
room.  Bleeding  is  to  take  place  from  the  tail 
which  now  requires  thorough  mechanical  cleans- 
ing. Warm  water  and  antiseptic  soap  are  applied 
freely  and  a  stiff  scrub-brush  is  used  to  work  up 
a  lather.  After  several  minutes  of  scrubbing,  the 
tail,  and  a  circular  area  surrounding  its  attach- 
ment, are  carefully  shaved.  The  body  of  the  ani- 
mal is  then  wet  to  settle  dust  that  may  be  con- 
tained in  its  coat,  and  a  cloth  dampened  in  anti- 


PLATE  11.  Bleeding  unit,  and  hog  prepared  for  bleeding,  but 
still  uncovered.  The  fruit  jar  and  breeding  horn  are 
clamped  together  and  sterilized  as  a  unit.  The  rubber 
cap  is  removed  from  the  mouth  of  the  horn  immediately 
before  the  latter  is  applied  to  the  hog's  tail.  New  York 
State  Veterinary  College  at  Cornell  University 


99 


100  HOG    CHOLEKA 

septic  solution  and  containing  a  hole  through 
which  the  tail  protrudes,  is  thrown  over  the  body. 
Thus  prepared,  the  animal  is  ready  for  the  bleed- 
ing room. 

Bleeding  is  accomplished  with  vacuum  which 
hastens  the  process  and  retards  coagulation.  The 
essential  bleeding  unit  consists  of  a  curved  metal 
horn,  one  end  armed  with  a  fitting  which  receives 
the  mouth  of  a  two-quart  fruit  jar,  forming  an  air 
tight  joint,  and  the  other  consisting  of  a  round 
or  oval-shaped  opening  presenting  a  moderately 
broad  surface  to  be  pressed  firmly  against  the  skin 
surrounding  the  tail,  which  member  the  horn  en- 
closes. Communicating  with  the  interior  of  the 
unit  is  a  tube  which,  continued  with  rubber  tubing, 
connects  with  a  pipe  leading  to  a  vacuum  tank. 
Somewhere  in  the  line  is  a  turncock  so  situated 
that  vacuum  may  be  employed  or  released  at  will, 
and  between  this  and  the  bleeding  unit  is  an  intake 
valve  fitted  with  a  small  cup  containing  carbolized 
cotton  through  which  air  must  pass  to  release  the 
vacuum  remaining  in  the  unit  when  bleeding  is 
completed  and  the  turncock  is  closed,  severing 
connection  with  the  vacuum  tank.  A  vacuum  indi- 
cator is  inserted  in  the  line  between  the  tank  and 
the  turncock. 

The  operator  grasps  the  tail,  disinfects  it  thor- 
oughly, and  dries  it  with  alcohol.  Then  with 
shears  designed  especially  for  the  purpose  an  inch 


PLATE  12.  Bleeding  for  p^rum.  Vacuum  is  applied  through  the 
rubber  tube,  and  the  blood  flows  into  the  jar.  1000  mils  of 
blood  can  be  drawn  in  about  8  minutes.  New  York  State 
Veterinary  College  at  Cornell  University 


101 


102  HOG    CHOLERA 

or  more  is  clipped  off  the  end,  and  the  part  re- 
maining is  guided  into  the  bleeding  horn,  which 
is  forced  tightly  against  the  body.  When  vacuum 
is  applied  the  contact  is  rendered  air-tight,  and 
blood  streams  rapidly  from  the  severed  tail. 
Moderate  and  uniform  traction  should  be  applied 
during  the  process  of  bleeding.  When  the  desired 
quantity  of  blood  has  been  drawn,  the  turncock 
is  closed,  the  vacuum  remaining  in  the  unit  is  re- 
leased through  the  intake  valve  already  described, 
and  the  tail  is  ligated  near  the  end  or  the  raw  sur- 
face is  seared  to  prevent  further  hemorrhage. 
It  is  well  to  cover  all  the  shaved  surfaces  with 
ointment  thus  preventing  chapping  of  the  skin 
which  may  render  subsequent  bleedings  difficult. 
Bleeding  technique  is  a  determining  factor  as 
far  as  cleanliness  of  the  serum  is  concerned,  and 
too  much  importance  cannot  be  attached  to  it. 
Thorough  mechanical  cleansing  of  the  tail  and 
surrounding  parts  is  a  first  essential.  Before  the 
razor  is  used,  warm  water  and  soap  should  be 
applied  vigorously  for  some  time,  thus  softening 
the  hair  and  removing  all  scurf.  Disinfecting  the 
tail  previous  to  bleeding  should  never  be  allowed 
to  degenerate  into  a  mere  perfunctory  process. 
During  the  bleeding  operation  every  effort  should 
be  made  to  prevent  the  vacuum  from  being  broken, 
for  this  admits  a  stream  of  air  which  may  be  con- 


PREPARATION    OF   ANTI-HOG-CHOLERA   SERUM       103 

taminated,  and  which,  in  any  event,  is  sure  to 
hasten  coagulation  of  the  blood. 

We  have  not  found  defibrinating  during  the 
bleeding  process  either  necessary  or  desirable.  If 
it  is  done  by  shaking  the  jar  into  which  the  blood 
is  flowing,  it  causes  the  hog  to  struggle,  thus  re- 
tarding the  bleeding  process  and  rendering  break- 
ing of  the  vacuum  imminent ;  and  if  it  is  done  by 
any  device  which  renders  shaking  unnecessary 
during  the  time  the  blood  is  being  drawn,  com- 
plete defibrination  can  be  brought  about  only  by 
shaking  the  jar  after  bleeding  is  discontinued. 
On  the  other  hand,  if  the  hog  is  allowed  to  lie  per- 
fectly quiet,  and  if  moderate  and  steady  traction 
is  applied  after  the  vacuum  is  established,  bleed- 
ing takes  place  rapidly,  and  almost  without  excep- 
tion perfect  defibrination  will  be  secured  if  the 
blood  is  shaken  immediately  after  bleeding  is  com- 
pleted. Individuals  differ,  but  the  average  hog 
bleeds  best  under  about  fifteen  inches  of  vacuum. 
Contrary  to  what  might  be  expected,  a  more  per- 
fect vacuum  than  this  usually  tends  to  retard 
bleeding  rather  than  to  hasten  it. 

Each  hyper  is  bled  once  each  week  during  a 
series  of  from  two  to  four  bleedings,  after  which 
it  may  be  rehypered  at  any  time.  In  rehypering 
only  21/2  mils  of  virus  per  pound  body  weight  are 
required.  Following  this  second  dose  of  virus  a 


104  HOG    CHOLEKA 

like  series  of  bleedings  takes  place,  the  first  oc- 
curring from  seven  to  ten  days  subsequent  to  re- 
hypering.  The  final  bleeding  takes  place  from  the 
throat  in  exactly  the  same  manner  in  which  virus 
pigs  are  bled,  except  that  the  blood  is  usually 
drawn  into  a  deep  porcelain  receptacle,  and  de- 
fibrinated  by  whipping  it  with  a  large  fork.  If 
inspection  does  not  disqualify,  the  blood  of  the 
hyper,  which  has  been  kept  separate  throughout 
the  two  series  of  bleedings,  is  admitted  to  test, 
and  the  carcass  is  placed  on  the  market. 

Handling  serum  blood.  Immediately  after  the 
bleeding  process  is  completed  the  jar  containing 
the  blood  is  sealed,  and  then  shaken  for  a  few 
moments  to  whip  out  the  fibrin.  When  this  proc- 
ess is  completed  the  jar  is  placed  in  ice- water. 
Later,  the  fibrin  is  separated  from  the  fluid  by 
exactly  the  same  process  that  is  employed  with 
virus  blood.  Here  again,  the  clot-press  is  detri- 
mental because  it  adds  superfluous  debris  to  the 
serum  and  causes  it  to  be  exposed  to  the  air  un- 
necessarily. After  the  defibrinated  blood  is 
strained  there  is  added  to  it,  as  a  preservative,  10 
mils  of  5  per  cent  aqueous  solution  of  carbolic 
acid  for  each  90  mils  of  blood.  The  product  is 
then  placed  in  storage  bottles,  labeled,  and  re- 
frigerated pending  the  time  when  enough  has 
accumulated  for  a  test. 

In  laboratories  which  do  not  clarify  the  serum, 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM       105 

the  blood  of  each  hyper  is  stored  separately  so 
that  if  the  animal  should  show  on  autopsy  general- 
ized tuberculosis  or  other  disqualifying  disease, 
the  blood  may  be  discarded.  Local  conditions 
must  govern  these  details.  In  our  own  laboratory 
where  it  is  possible  to  purchase  hypers  which 
have  not  followed  cattle  and  have  not  been  fed  raw 
creamery  products,  we  always  mix  bleedings,  in 
spite  of  the  fact  that  we  do  not  clarify  the  serum. 
We  have  never  had  a  hyper  show  generalized 
tuberculosis,  and  in  the  few  instances  in  which 
we  have  found  the  disease  localized,  we  have  used 
a  guinea-pig  test  to  determine  the  fitness  of  the 
serum  for  market.  We  believe  this  test  has  a 
wider  application  than  is  now  accorded  it. 

FINAL   PROCESSES    IN    SERUM    PRODUCTION 

Testing.  Irrespective  of  detail  in  preparation, 
the  final  requirement  is  that  the  finished  product 
shall  pass  a  test  proving  its  protective  potency 
under  carefully  controlled  conditions.  For  this 
purpose  there  is  drawn  a  sample  from  a  mixed  lot 
consisting  usually  of  about  100,000  mils  of  serum. 
Seven  pigs  weighing  between  45  and  90  pounds 
each  are  selected  for  the  official  Bureau  of  Animal 
Industry  test.  Temperatures  must  be  normal  and 
all  pigs  in  good  physical  condition  at  the  time  the 
test  begins.  Each  pig  is  given  2  mils  of  hog 
cholera  virus,  five  of  them  receiving  in  addition, 


106  HOG   CHOLEEA 

and  at  the  same  time,  20  mils  each  of  the  sample 
of  serum  to  be  tested.  The  other  two  receive  no 
serum,  but  are  employed  as  controls  to  determine 
the  virulence  of  the  virus.  Daily  observations  are 
made  and  temperatures  are  recorded  as  required, 
preferably  once  a  day.  The  essential  require- 
ments for  a  satisfactory  test  are  that  both  pigs 
which  receive  virus  only  shall  sicken  during  the 
test  period  (21  days)  and  that  at  least  one  of  them 
shall  sicken  between  the  fourth  and  seventh  days 
subsequent  to  injection,  and  shall  before  the  fif- 
teenth day  suffer  from  hog  cholera  in  a  degree 
sufficient  to  cause  death.  As  an  additional  con- 
dition, no  more  than  one  of  the  pigs  that  receive 
serum  and  virus  shall  show  visible  illness,  and  in 
case  one  should  sicken  it  must  be  completely  re- 
covered before  the  twenty-first  day  following  the 
beginning  of  the  test. 

Bureau  of  Animal  Industry  regulations  govern- 
ing the  interpretation  of  tests  will  be  found  in  the 
Appendix.  In  general,  tests  are  classified  accord- 
ing to  results  as  '  '  satisfactory, "  "unsatisfac- 
tory" or  "no  test,"  the  latter  giving  indefinite 
results.  The  satisfactory  test  has  already  been 
described;  the  unsatisfactory  test  is  usually  re- 
ferred to  impotent  or  contaminated  serum;  re- 
tests  are  indicated  when  the  serum-treated  pigs 
or  more  than  one  of  the  virus  pigs  sicken  before 
the  fourth  day,  when  the  control  pigs  do  not  sicken 


107 


108  HOG    CHOLEEA 

as  is  required  in  a  satisfactory  test,  or  when  inter- 
current  disease  or  accident  intervenes. 

Too  much  stress  cannot  be  placed  on  the  test, 
for  it  is  here  that  all  technique  leading  up  to  com- 
pletion of  the  finished  product  receives  its  final 
confirmation.  Careful  observations  are  necessary 
as  well  as  strict  interpretations  which  withhold 
from  use  all  doubtful  serum.  Regulations  are  a 
valuable  guide,  but  they  themselves  require  skill- 
ful interpretation,  and  no  exact  rules  can  be  laid 
down  which  will  serve  their  intended  purpose 
under  all  circumstances.  Is  the  serum  highly  po- 
tent? Is  it  free  from  organisms  that  will  injure 
hogs  into  which  it  is  injected?  When  test  con- 
ditions answer  both  questions  definitely  in  the 
affirmative,  the  serum  is  fit  for  use.  If  doubt  re- 
mains it  may  be  retested,  and  if  it  has  failed  to 
protect  healthy  pigs  in  average  condition  it  should 
be  discarded. 

In  our  own  work  we  greatly  prefer  an  eight  pig 
test  in  which  two  of  the  serum  pigs  receive  10 
mils  each  of  serum,  two  15  mils  each,  and  two 
others  20  mils  each.  We  believe  that  these  low 
doses  give  much  more  complete  information  re- 
garding the  potency  of  the  product,  thus  allowing 
a  greater  margin  of  safety  and  adding  to  the  con- 
fidence with  which  it  may  be  used  in  the  field. 
Out  of  the  last  45  tests  conducted  in  this  manner 
37  have  passed  without  incident,  intercurrent  dis- 


PREPARATION    OF   ANTI-HOG-CHOLERA'  SERUM       109 

ease  (heavy  ascaris  infestation)  necessitated 
three  retests  which  were  satisfactory,  one  10  mil 
serum  pig  died  in  each  of  two,  one  15  mil  pig  died 
in  one,  and  two  were  wholly  unsatisfactory  due  to 
low  potency.  The  test  pigs  ranged  in  weight  be- 
tween 27  and  105  pounds,  the  average  being  59. 

It  is  of  advantage  to  select  test  pigs  from  herds 
in  which  no  immunizing  has  been  done  and  in 
which  hog  cholera  has  not  appeared  in  recent 
years.  It  is  well  if  all  pigs  in  a  single  test  can 
be  litter  mates.  The  pigs  should  not  be  subjected 
to  long  hauls  just  before  they  go  on  test,  and  dur- 
ing the  test  great  care  is  necessary  to  prevent 
overfeeding  of  the  serum  pigs  at  the  time  when 
their  reaction  begins,  which  is  about  the  time  the 
virus  pigs  refuse  feed  entirely.  As  a  routine 
measure  it  is  a  good  plan  to  reduce  the  feed  one- 
third  or  one-half  on  the  morning  of  the  fourth  day 
of  test,  and  to  feed  subsequently  so  that  the  serum 
pigs  are  kept  just  a  little  hungry. 

It  is  interesting  and  highly  instructive  to  ob- 
serve the  progress  of  a  series  of  tests,  and  we 
know  that  some  field  workers  would  be  more  cau- 
tious in  their  vaccinating  if  this  experience  could 
be  theirs.  It  is  in  this  manner  that  we  see  results 
of  the  battle  between  protective  and  destructive 
forces,  and  are  brought  to  realize  how  easy  it  is 
for  some  disturbing  factor  to  turn  the  tide  in 
favor  of  destruction.  The  virus  pigs  usually  show 


110  HOG   CHOLEBA 

a  temperature  near  106°  F.  on  the  fourth  or  fifth 
day  of  the  test,  and  this  high  level  is  maintained 
several  days.  Other  symptoms  of  hog  cholera  ap- 
pear a  day  or  two  after  the  temperature  curve 
starts  upward.  The  pigs  which  receive  protective 
serum  in  addition  to  virus  also  undergo  a  reaction, 
which  is  slightly  delayed  and  very  mild  as  com- 
pared to  that  observed  in  the  virus  pigs.  In  some 
instances  no  temperature  reaction  is  discernible, 
but  usually  readings  reach  a  point  between  104° 
and  105°  F.,  considerable  fluctuation  between  nor- 
mal and  this  level  being  observed.  As  a  rule  the 
casual  observer  would  detect  no  evidence  of  a 
physical  reaction,  but  not  infrequently  the  appe- 
tite lags  just  perceptibly  for  two  or  three  days 
and  in  white  pigs  a  slight  flush  may  be  observed 
in  the  skin.  On  the  whole,  all  evidence  of  reaction 
has  usually  disappeared  from  the  serum  pigs  be- 
fore the  tenth  day  of  the  test. 

According  to  Bureau  of  Animal  Industry  regu- 
lations, serum  which  protects  in  doses  required  in 
their  official  test  is  suitable  for  use  in  the  field 
under  a  dosage  label  as  follows : 

Sucking  pigs 20  mils 

Pigs,  20  to  40  pounds 30  mils 

Pigs,  40  to  90  pounds 35  mils 

Pigs,  90  to  120  pounds 45  mils 

Pigs,  120  to  150  pounds 55  mils 

Hogs,  150  to  180  pounds 65  mils 

Hogs,  180  pounds  and  over 75  mils 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM       111 

Bottling  and  labeling.  After  a  lot  of  serum 
has  passed  a  satisfactory  test  it  remains  to  place 
it  in  bottles  of  suitable  size  for  shipping.  In 
large  laboratories  this  is  done  with  machines  de- 
signed especially  for  the  purpose ;  in  smaller  ones 
it  is  done  by  placing  the  serum  in  a  large  covered 
container  drained  by  a  tubular  outlet  on  which  is 
fitted  a  few  inches  of  rubber  tubing.  This  tubing 
terminates  in  a  small  umbrella-shaped  aluminum 
device,  the  serum  flowing  through  the  part  repre- 
senting the  handle,  and  the  bottle  being  protected 
from  dust  during  the  filling  process  by  the  part 
representing  the  cover.  All  bottles  intended  for 
shipping  are  sealed  and  placed  in  the  refrigerator 
until  they  are  needed. 

A  label  should  be  placed  on  every  bottle  of  se- 
rum shipped,  and  should  include : 

1.  Eelease  tag  and  license  number  if  the  labora- 
tory is  being  operated  under  federal  license. 

2.  Name  and  address  of  manufacturing  firm  or 
institution. 

3.  Dosage  table. 

4.  Identification  mark,  which  will  enable  the 
manufacturer  to  trace  the  exact  history  of  any 
bottle  of  serum. 

5.  Return  date,  or  latest  date  on  which  the  se- 
rum may  safely  be  used. 

6.  Brief  directions  for  use  and  caution  regard- 
ing methods  of  preservation. 


112  HOG   CHOLEBA 

The  finished  product.  It  has  already  been 
shown  that  all  serum  sent  out  is,  or  should  be, 
subjected  to  carefully  controlled  tests  in  which  it 
is  required  to  protect  laboratory  pigs  in  much 
smaller  doses  than  would  be  administered  to  like 
animals  in  the  field.  The  protective  defibrinated 
blood,  called  anti-hog-cholera  serum,  is  the  basic 
preparation  from  which  all  the  more  or  less  re- 
fined products  now  on  the  market  take  origin,  and 
when  it  is  prepared  with  careful  technique  it  is  in 
the  original  state  a  highly  effective  and  safe  im- 
munizing agent.  It  may  or  may  not  be  sterile. ' 

Clear  serum  is  "bloody  serum"  minus  blood 
corpuscles.  It  is  prepared  from  the  protective 
defibrinated  blood  by  various  combinations  of 
processes  which,  individually  considered,  include 
precipitation  of  the  red  blood  corpuscles  with 
navy  bean  extract,  centrifuging,  and  filtering 
through  various  materials.  Heat,  60°  C.,  for  one- 
half  hour,  is  applied,  which  kills  some  contaminat- 
ing organisms  that  may  be  present.  An  impres- 
sion seems  to  prevail  that  all  clear  serum  is  sterile, 
but  this  is  not  true,  for  it  is  not  necessarily  sub- 
jected to  temperatures  or  other  treatment  which 
will  kill  or  remove  all  living  bacteria. 

The  comparative  merits  of  clear  and  "bloody" 
serum  are  the  subject  of  much  controversy,  but  as 
is  true  of  other  things  of  like  nature,  individual 
methods  are  the  deciding  factor.  Clear  serum, 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM        113 

if  not  subsequently  diluted  may  be  administered 
in  somewhat  smaller  doses  than  can  "bloody" 
serum,  it  is  free  from  extraneous  matter  which 
has  no  immunizing  value,  and  all  other  things 
being  equal  it  is  more  likely  to  be  sterile.  On  the 
other  hand  it  usually  becomes  cloudy  on  standing, 
its  keeping  qualities  and  continued  potency  after 
heating,  so  often  emphasized,  are  yet  to  be  fully 
established,  and  it  is  more  expensive  than  the 
"bloody"  serum.  "Bloody"  serum  contains  cor- 
puscles which  are  of  no  value  in  immunizing,  and, 
like  the  clear  serum,  if  it  is  not  carefully  prepared 
it  may  also  contain  excessive  numbers  of  bac- 
teria. On  the  other  hand  it  is  not  subjected  to 
complicated  processes  which  invite  error  in  tech- 
nique, and  it  can  be  prepared  much  more  cheaply, 
per  immunizing  unit,  than  clear  serum. 

Disregarding  entirely  the  form  of  the  finished 
product,  the  test,  conscientiously  applied  and 
skillfully  interpreted,  is  the  swine  breeder's  guar- 
antee of  safety  to  his  herd.  Thus  either  clear  or 
"bloody"  serum,  carefully  prepared,  is  a  safe  and 
effective  immunizing  agent;  neither,  carelessly 
prepared,  will  produce  the  results  the  breeder  and 
his  veterinarian  have  a  right  to  expect. 

The  relative  merits  of  tail-bled  and  carotid-bled 
serum  have  also  been  the  subject  of  much  absurd 
controversy,  for  no  scientific  evidence  has  ever 
been  submitted  to  prove  one  product  different 


114  HOG   CHOLERA 

from,  or  superior  to,  the  other.  Carotid-bled  se- 
rum is  a  mere  "talking  point. "  Some  laborato- 
ries situated  near  stockyards  can  produce  it  more 
cheaply  than  they  can  produce  the  tail-bled  prod- 
uct, and  this  fact,  rather  than  considerations 
based  on  the  quality  of  the  product,  explains  their 
preference  for  carotid-bled  serum.  Both  products 
pass  like  tests  before  being  released  for  use. 

The  keeping  qualities  of  anti-hog-cholera 
serum  vary  with  different  lots,  and  with  various 
methods  of  preparing  and  storing.  Bureau  of 
Animal  Industry  regulations  place  the  expiration 
date  at  two  years  from  the  time  the  first  bleeding 
in  a  particular  lot  takes  place,  and  subject  to  satis- 
factory retest  at  the  end  of  two  years,  another 
year  may  be  added.  Our  own  preference  is  for  a 
shorter  period,  for  in  one  or  two  instances  we 
have  known  serum  to  fall  away  in  potency  before 
it  was  two  years  old. 

Serum  should  always  be  stored  in  a  dark,  cool 
place.  According  to  a  limited  number  of  tests 
conducted  by  Kernkampf,  freezing  does  not  in- 
jure it,  but  temperatures  below  the  freezing  point 
are  not  desirable.  A  temperature  between  40° 
and  55°  F.  seems  to  be  most  favorable.  After  the 
seal  on  a  bottle  has  been  broken  and  a  portion  of 
the  serum  removed,  the  remainder  should  be  used 
in  the  course  of  a  few  days,  or  discarded.  It  is 
always  well  to  open  the  bottle  out  of  doors,  if  all 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM       115 

the  serum  contained  in  it  is  not  required  for  im- 
mediate use. 

The  scope  and  purpose  of  this  book  do  not  allow 
further  detail  which  might  profitably  be  included 
in  a  more  inclusive  text.  In  leaving  the  subject 
of  serum  production,  let  us  emphasize  again  a 
few  essentials  which  make  for  clean,  potent  serum. 
These  include  strong  vigorous  hypers  that  have 
been  immune  to  hog  cholera  a  long  time  before 
being  hypered;  a  highly  virulent  strain  of  virus 
that  will  " ripen'*  pigs  to  kill  in  seven  days,  or 
less;  scrupulous  cleanliness  and  strict  antisepsis 
in  all  operations;  rapid  cooling  of  all  blood  im- 
mediately after  it  is  drawn ;  no  unnecessary  han- 
dling or  exposure  of  serum  during  the  process  of 
defibrinating  and  straining;  and  finally,  careful 
observation  of  tests,  with  positive  exclusion  of 
doubtful  serum. 

Hog  Cholera  Virus 

Hog  cholera  virus,  called  by  the  trade  "simul- 
taneous virus "  because  it  is  used  in  the  field  in 
conjunction  with  protective  serum,  is  produced 
by  giving  shoats  doses  of  virus  (usually  2  mils 
each),  allowing  them  to  sicken,  and  drawing  their 
blood  while  the  disease  is  at  its  height.  This  blood 
is  handled  in  exactly  the  same  manner  as  hyper- 
ing  virus,  differing  from  this  latter  product  only 
in  that  there  is  added  to  it  as  a  preservative,  5 


116  HOG    CHOLEEA 

mils  of  5  per  cent  aqueous  solution  of  carbolic  acid 
for  each  95  mils  of  blood.  The  pigs  used  to  pro- 
duce simultaneous  virus  must  meet  the  same  es- 
sential requirements  as  are  met  by  those  used  to 
produce  hypering  virus;  that  is,  they  must  show 
ample  evidence  that  they  are  suffering  with  acute 
hog  cholera  at  the  time  they  are  bled,  and  they 
must  be  free  of  all  other  infectious  diseases  trans- 
missible through  their  blood. 

Hog  cholera  virus  is  sometimes  heated  at  50°  C. 
for  twelve  hours  before  being  sent  out,  in  which 
case  a  virulence  test  is  necessary  before  it  can 
be  released  for  field  use.  In  our  own  work  we 
greatly  prefer  unheated  virus. 

Keeping  qualities.  Like  protective  serum,  hog 
cholera  virus  must  be  kept  in  a  dark,  cool  place. 
Bureau  of  Animal  Industry  regulations  allow  it 
to  be  used  not  more  than  sixty  days  subsequent  to 
the  date  of  drawing,  but  wherever  a  thirty-day 
limit  is  practicable,  we  believe  it  is  safer.  There 
are  times  when  an  inactive  virus  may  result  in  as 
heavy  losses  as  are  sometimes  charged  to  impo- 
tent serum. 

Labeling.    The  virus  label  should  include: 

1.  Eelease  tag  and  license  number  if  the  labora- 
tory is  operated  under  federal  license. 

2.  Name  and  address  of  manufacturing  firm  or 
institution. 

3.  Dosage  table. 


PREPARATION    OF    ANTI-HOG-CHOLERA   SERUM       117 

4.  Identification  mark,  enabling  the  manufac- 
turer to  trace  the  exact  history  of  any  bottle  of 
virus. 

5.  Eeturn  date,  or  latest  date  on  which  the  virus 
may  safely  be  used. 

6.  Directions  for  storing. 

7.  Brief  directions  for  using,  and  cautions  to 
be  observed  in  destroying  unused  virus. 

Hog  cholera  virus  is  dangerous  material.  One- 
half  mil  or  even  less  will  readily  kill  an  ordinary 
susceptible  hog  if  protective  serum  is  not  admin- 
istered in  conjunction  with  it.  Thus  hogs  given 
simultaneous  treatment  in  the  field  actually  re- 
ceive, as  a  routine  measure,  a  lethal  dose  of  virus. 
It  is  really  remarkable  that  this  practice  results 
in  so  little  trouble,  but  potential  danger,  slight 
though  it  is,  exists  whenever  virus  is  used,  and 
this  fact  should  be  well  understood  both  by  the 
veterinarian  and  his  client.  Under  no  circum- 
stances should  virus  be  used  by  untrained  men. 


CHAPTER  VIII 

METHODS   OF   USING   ANTI-HOG-CHOLERA   SEBUM 

Confining  the  animals.  We  will  consider  first 
methods  of  confining  the  animals  to  be  treated. 
To  one  unaccustomed  to  handling  hogs  the  task 
of  confining  and  vaccinating  a  large  herd  of  swine 
seems  formidable,  and  not  infrequently  the  diffi- 
culties presented,  although  largely  imaginary, 
have  led  to  costly  neglect  or  procrastination. 
Chasing  hogs  to  catch  them  is  usually  futile,  it  is 
time  consuming,  and  if  double  treatment  is  to  be 
applied,  or  if  the  animals  are  fat,  the  practice  is 
positively  dangerous.  Ingenuity  is  required,  and 
the  veterinarian  who  can  use  the  help  and  ma- 
terials at  hand  to  best  advantage,  enabling  him  to 
vaccinate  a  herd  quietly  and  rapidly,  and  without 
exciting  the  animals,  gains  much  in  the  confidence 
of  his  clients. 

If  the  time  that  vaccinating  is  to  be  done  is 
known  to  veterinarian  and  client  the  latter  should 
tempt  the  animals  into  pens  or  small  enclosures 
with  feed  and  fasten  them  in  securely.  Bedding 
should  be  provided  so  that  the  hogs  will  be  clean 
and  dry.  In  cases  of  emergency,  where  this  ad- 

118 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SEKUM        119 

vance  knowledge  is  lacking  hurdles  should  be  used 
to  crowd  the  animals  into  the  corner  of  a  yard  or 


PLATE  14.     Injecting  anti-hog-cholera  serum  in  the  ham 

pasture.  In  all  cases  in  which  fences  are  insecure 
it  is  important  to  mark  each  animal  at  the  time  it 
is  vaccinated,  so  that  if  treated  and  untreated  ones 


120 


HOG    CHOLERA 


should  accidentally  get  together  identification  will 
still  be  possible.  Paint,  chalk,  bluing  or  tincture 
of  iodin  are  convenient  for  this  purpose,  or  if  a 


PLATE  15.     Method    of    holding    shoat    for    injecting 
serum  in  axillary  space 

permanent    mark   is    desired,    the    ear   may   be 
notched. 

Assuming  that  the  animals  are  fastened  in  small 
pens  when  the  veterinarian  arrives,  confinement 
of  the  individual  during  the  process  of  immuniza- 


METHODS    OF    USING   ANTI-HOG-CHOLERA    SERUM        121 

tion  is  the  next  step.  As  a  site  of  injection,  one 
may  select  the  armpit,  medial  surface  of  the  thigh, 
or  the  area  immediately  behind  the  ear.  The  site 


PLATE    16.     An    improvised    method    of    holding    shoats    for 
immunizing.     Injecting  serum  in  axillary  space 

chosen,  the  size  of  the  animal  and  individual  pref- 
erences determine  the  method  of  holding.  If  the 
site  is  to  be  the  medial  surface  of  the  thigh,  any 


122 


HOG    CHOLEEA 


pig  weighing  less  than  sixty  pounds  may  be  seized 
by  the  hind  legs  and  held  with  the  head  suspended, 
belly  toward  the  operator.  If  the  armpit  is 
chosen  the  pig  is  suspended  by  the  front  legs 
which  are  drawn  well  apart. 

Shoats  weighing  more  than  sixty  pounds  are 
confined  in  a  variety  of  ways.  Sometimes  they 
are  thrown  and  held  on  their  backs;  sometimes 
two  men  suspend  them  by  their  hind  legs ;  at  other 
times  it  is  convenient  to  incline  a  V-shaped  hog 
trough  against  a  fence  so  that  it  forms  an  angle  of 
about  45  degrees  with  the  ground.  Into  this  the 
shoats  are  placed  on  their  backs,  heads  downward, 
and  their  snouts  are  allowed  to  slide  under  a  cleat 
which  extends  across  it.  Perhaps  the  most  serv- 
iceable method  of  handling  animals  of  this  size  is 
to  seize  them  by  the  front  legs  and  set  them  on 
their  haunches  with  their  backs  drawn  firmly 
against  the  legs  and  body  of  the  man  holding 
them.  In  this  position  they  are  quite  helpless  and 
they  are  easily  held  as  their  weight  rests  entirely 
on  the  ground.  Shoats  thus  confined  are  injected 
in  the  armpit. 

In  throwing  larger  hogs  that  are  to  be  held  on 
their  backs  for  treatment  it  is  well  to  seize  them 
by  the  front  leg  on  the  nearest  side.  A  common 
mistake  is  to  reach  under  them  for  the  off  foreleg. 
Another  convenient  and  surprisingly  easy  method 
of  throwing  is  to  seize  the  tail  with  the  right  hand 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SEBUM        123 

and  the  left  hind  leg  with  the  left,  pulling  down- 
ward and  to  the  right  on  the  tail,  upward  and  to 
the  left  on  the  leg.  Like  the  double  half -hitch  in 
throwing  a  bull,  this  method  of  throwing  hogs  is 
effective,  but  its  manner  of  action  is  a  mystery. 

Large  hogs  are  seldom  thrown  but  are  confined 
either  by  means  of  a  noosed  rope  which  is  placed 
well  back  in  the  mouth  and  tightened  around  the 
snout,  or  with  one  of  the  many  types  of  hog-hold- 


PLATE  17.  Convenient  hog  holder  made  from  %  inch  gas  pipe 
and  flexible  clothes  wire.  It  may  be  disjointed  in  the 
middle  for  convenience  in  carrying 

ers.  In  case  a  snout-rope  is  used  it  should  be 
either  14  or  %  inches  in  diameter,  and  about  fif- 
teen feet  long.  An  eye  about  %  inches  in  diame- 
ter is  braided  in  one  end,  and  through  this  the 
other  end  of  the  rope  is  passed  to  make  a  running 
noose.  Directly  around  the  rope  forming  the 
noose  is  braided  a  jerk-rope  about  a  foot  long. 
This  device  renders  it  possible  to  release  a  hog 
instantly,  and  saves  time,  for  if  it  is  not  used  re- 
leasing the  animal  sometimes  is  as  difficult  as 
confining  it.  A  large  rope  tied  in  any  manner  to 


124  HOG    CHOLEKA 

form  a  running  noose  is  clumsy  to  handle,  and 
allows  a  great  many  animals  to  escape. 

There  is  a  great  knack  in  noosing  the  snout  of 
a  large  hog.    Assuming  that  a  person  is  right- 


PLATE  18.  Method  of  preparing  snout  rope  for  confin- 
ing large  hogs.  The  short  "jerk-rope"  renders  it 
possible  to  release  the  hog  instantly.  ^4  or  %  inch 
Manila  rope  is  used 

handed  he  should  stand  near  the  center  of  the  pen 
and  start  the  animal  moving  around  it  to  the  left, 
at  the  same  time  seeking  a  position  at  the  hog's 
left  shoulder.  Holding  in  readiness  a  short  sec- 
tion of  the  noose,  and  at  the  same  time  crowding 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SEBUM        125 

the  hog  suddenly  and  forcibly  against  the  side  of 
the  pen  with  the  right  leg,  one  takes  advantage 
of  the  fact  that  the  animal  opens  its  mouth  to 
squeal  or  champ  its  teeth  when  its  progress  is  thus 
momentarily  arrested.  The  noose  is  slipped  into 
the  mouth,  drawn  backward  quickly,  and  tightened 


PLATE  19.  Method  of  noosing  the  snout  of  hog.  The  animal 
is  forced  suddenly  against  the  gate  with  the  right  knee, 
the  noose  is  thrust  into  the  mouth,  drawn  behind  the 
canine  teeth  and  tightened 

around  the  snout.  The  free  end  of  the  rope  is 
then  secured  and  the  animal  is  tapped  on  the  snout 
to  make  it  pull  backward,  for  a  hog  will  not  stand 
quietly  unless  the  rope  is  tight.  In  this  position 
the  site  of  injection  behind  the  ear  is  readily 
available.  When  a  sow  and  sucking  pigs  are  to 


126  HOG    CHOLERA 

be  immunized,  the  sow  should  be  tied  and  injected 
first,  and  released  only  after  the  pigs  have  been 
vaccinated. 

Another  method  of  confining  large  hogs  is  to 
connect  two  pens  with  a  narrow,  low  chute,  which 
can  be  closed  at  both  ends.  Into  this  a  limited 
number  of  hogs  are  crowded  tightly  as  they  pass 
from  one  pen  to  the  other,  and  the  operator  may 
reach  over  the  side  of  the  chute  and  inject  the 
animals  behind  the  ear.  This  involves  some  labor 
in  preparation,  but  it  is  a  rapid  method  of  han- 
dling, and  may  be  serviceable  when  a  large  num- 
ber of  hogs  are  to  be  immunized.  Quiet  hogs  may 
sometimes  be  injected  without  resorting  to  noose 
or  holder  as  the  operation  is  by  no  means  painful. 

Methods  of  Using  Serum 

Preventive  vaccination  against  hog  cholera  in- 
volves the  use  of  just  two  materials;  anti-hog- 
cholera  serum,  which  is  protective  in  nature,  and 
which  is  prepared  from  the  blood  of  hogs  that  are 
hyperimmune  to  cholera;  and  hog  cholera  virus 
which  is  the  defibrinated  and  preserved  blood  of 
pigs  that  are  suffering  with  hog  cholera  at  the 
time  bleeding  takes  place.  With  these  two  ma- 
terials three  methods  of  immunizing  have  been 
developed;  serum  alone,  simultaneous  (double,  or 
serum- virus),  and  follow-up,  which  is  a  combina- 
tion of  the  two  first-named  methods. 


METHODS   OF   USING   AN TI- HOG- CHOLERA   SERUM        127 

The  practicing  veterinarian  is  regularly  re- 
quired to  select  the  method  best  suited  to  the 
conditions  he  encounters,  and  he  can  handle  hog 
cholera  with  maximum  efficiency  only  when  he 
judiciously  chooses  and  employs  the  particular 
method  indicated.  The  selection  is  based  entirely 
on  the  effects  produced  by  each  method,  just  as  we 
choose  drugs  on  the  basis  of  their  action.  When 
once  these  effects  are  well  understood,  the  choice 
involves  no  great  difficulties. 

Serum  alone  method.  This  consists  of  deep 
injection  of  the  required  quantity  of  serum.  If 
the  animals  thus  treated  are  not  infected  l  with 
hog  cholera  immediately  before  or  during  the  four 
weeks  following  serum  administration  the  immu- 
nity conferred  may,  with  rare  exceptions,  be  de- 
pended on  four  weeks.  In  many  individuals  it 
lasts  much  longer.  Swine  more  than  twelve  weeks 
old  that  receive  serum  alone  and  are  infected  with 
cholera  immediately  before  immunization,  or  dur- 
ing the  three  or  four  weeks  following,  are  there- 
after permanently  immune.  The  effect  on  pigs 
less  than  twelve  weeks  old  is  still  a  matter  of  con- 
troversy, but  at  present  we  are  not  safe  in  depend- 

1  Much  misunderstanding  has  arisen  because  of  the  loose  use 
of  the  terms  "infected"  and  "exposed."  The  first  term  implies 
that  hog  cholera  virus  sufficient  to  produce  the  disease  has  actually 
entered  the  system;  the  second  implies  that  the  animal  has  been 
in  close  contact  with  virus  from  any  source,  but  infection  may 
or  may  not  have  taken  place.  Hogs  given  serum  alone  and  in- 
fected with  hog  cholera  acquire  a  permanent  immunity;  if  they 
are  exposed  but  not  actually  infected  the  immunity  is  temporary. 


128  HOG   CHOLEKA 

ing  on  serum  alone  plus  natural  infection  to  pro- 
tect young  pigs  more  than  four  weks. 

Technique  of  serum  administration.  Require- 
ments. Serum  in  covered  container,  or  in  a  bottle 
fitted  with  cannula  through  which  it  may  be 
drawn;  hypodermic  needles,  and  syringe,  the  lat- 
ter preferably  one  of  30  or  40  mil  capacity ;  anti- 
septic solution  in  large  container,  and  scrub-brush, 
for  disinfecting  site  of  injection;  antiseptic  solu- 
tion in  small  container  for  disinfecting  needles  and 
syringe.  In  field  work  these  are  placed  conven- 
iently upon  an  improvised  table  consisting  usually 
of  a  box  covered  with  a  clean  towel  or  oilcloth. 

The  pig  is  confined  in  the  manner  already  de- 
scribed, and  the  site  of  injection  is  thoroughly 
cleansed  with  the  scrub-brush  dampened  in  anti- 
septic. If  syringe  and  needles  have  not  been  pre- 
viously sterilized,  they  should  now  be  thoroughly 
disinfected,  after  which  the  required  quantity  of 
serum  is  drawn  into  the  syringe  and  injected 
deeply  into  the  tissues.  As  the  needle  is  with- 
drawn it  is  well  to  pinch  the  skin  to  prevent  back- 
ward flow  of  serum.  Massage  is  now  applied  if 
required,  the  site  of  injection  is  again  dampened 
in  antiseptic,  and  the  pig  is  released. 

Choice  of  the  site  of  injection  is  governed  by 
the  size,  condition  and  intended  use  of  the  animal, 
by  the  method  of  confining,  and  by  individual 
preferences.  All  other  things  being  equal  we  pre- 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SEBUM        129 

fer  the  armpit  because  the  skin  covering  it  is 
usually  clean,  the  serum  enters  the  tissues  freely, 
and  with  each  step  the  animal  takes,  massage  is 
automatically  applied.  Very  young  pigs  are  most 


PLATE  20.  Injecting  serum  behind  the  ear.  The  needle  is  thrust  deeply 
into  the  loose  areolar  tissues,  and  very  little  force  is  required  to 
expel  its  contents 

conveniently  confined  for  injecting  in  the  ham. 
Heavy  hogs,  especially  pregnant  sows,  are  almost 
always  injected  behind  the  ear,  because  it  is  safer 
and  more  convenient  to  confine  them  standing. 
Hogs  nearly  ready  for  market  should  not  be  in- 


130  HOG    CHOLERA 

jected  in  the  ham,  and  young  pigs  and  shoats  are 
not  injected  behind  the  ear.  Sometimes  serum 
is  administered  in  the  flank,  or  in  the  loose  tissues 
immediately  back  of  the  elbow,  but  we  believe 
neither  practice  has  much  to  recommend  it. 

Rapid  and  complete  absorption  of  serum  is 
greatly  to  be  desired,  because  it  gives  the  highest 
and  most  prompt  immunizing  effect,  and  tends  to 
prevent  abscess  formation.  Some  will  inject  no 
more  than  20  mils  of  serum  in  a  place,  believing 
that  a  greater  quantity  will  be  absorbed  but 
slowly,  but  it  is  the  placing  and  distribution  of 
the  dose,  much  more  than  its  size,  that  govern  ab- 
sorption. In  real  small  pigs  it  is  well  to  divide 
the  dose,  and  whenever  possible  the  practice  may 
be  followed  in  older  animals.  In  injecting  young 
pigs  the  parts  that  receive  the  serum  should  be 
kneaded  gently  after  the  needle  is  withdrawn;  in 
larger  animals  the  needle  should  be  thrust  deeply 
into  the  loose  tissues  immediately  behind  the  ear, 
and  after  the  injection  is  completed  the  ear  should 
be  drawn  forward  and  vigorous  massage  applied 
in  order  to  distribute  the  dose.  Serum  injected 
immediately  beneath  the  skin,  forming  a  distinct 
welt,  absorbs  but  slowly,  and  when  it  fails  to 
spread  in  the  deeper  tissues,  as  evidenced  by  un- 
due pressure  required  in  making  the  injection, 
rapid  absorption  cannot  be  expected.  A  syringe 


METHODS    OF   USING   ANTI-HOG-CHOLERA   SEBUM        131 

which  operates  easily  and  requires  uniform  pres- 
sure on  the  plunger  should  always  be  selected. 

Cleaning  and  disinfecting  the  site  of  injection 
are  processes  frequently  neglected,  because  the 
hog  is  proverbially  difficult  to  infect.  He  can  be 
infected  though,  as  some  have  found  to  their  sor- 
row. If  hogs  are  at  pasture  or  in  clean,  dry,  well- 
bedded  pens,  cleaning  is  not  difficult.  Some  sim- 
ply paint  the  skin  with  tincture  of  iodin,  and  this 
answers  well  when  the  site  of  injection  is  both 
dry  and  clean,  but  tincture  of  iodin  is  not  suitable 
for  use  on  wet  surfaces.  We  have  found  nothing 
better  than  a  good  coal-tar  disinfectant  applied 
with  a  stiff  scrub-brush,  for  this  removes  all  dirt 
and  scurf,  in  addition  to  furnishing  the  desired 
antiseptic  action.  If  pigs  are  unusually  dirty  the 
site  of  injection  should  first  be  cleaned  with  warm 
soapsuds.  Good  technique  includes  thorough  me- 
chanical cleansing,  and  nothing  else  will  take  its 
place. 

Dosage  of  serum.  The  best  rule  is  to  give  at 
least  as  much  serum  as  the  label  requires.  Serum 
varies  widely  in  immunizing  units  per  mil,  and 
although  the  margin^  of  safety — the  increase  of 
the  field  dose  over  the  laboratory  test  dose — ob- 
served in  individual  laboratories  is  not  the  same, 
doses  recommended  in  any  particular  laboratory 
are,  in  a  very  general  way,  determined  by  its  indi- 


132  HOG   CHOLERA 

vidual  methods  of  preparing  and  testing.  Dosage 
is  based  on  weight,  and  one  not  accustomed  to 
estimating  weights  of  hogs  should  weigh  one  or 
more  before  beginning  work,  for  a  common  and 
disastrous  error  is  to  estimate  far  too  low,  and 
to  give  correspondingly  small  doses  of  serum. 
Not  infrequently  we  have  known  weights  to  be 
estimated  at  less  than  half  what  they  actually 
were.  We  believe  a  common  error  in  dosing,  and 
one  for  which  labels  are  frequently  responsible, 
consists  of  giving  all  hogs  above  a  certain  weight 
a  fixed  quantity  of  serum.  Thus  on  one  label  we 
read:  "Hogs  180  pounds  and  over,  75  mils,"  A 
hog  weighing  180  pounds  may  properly  receive 
75  mils  of  average  serum,  but  one  weighing  500 
pounds  will  not  be  adequately  protected  by  that 
quantity.  Under  all  conditions  under  which  it  is 
known  or  suspected  that  the  hogs  have  resistance 
below  the  average,  it  is  a  wise  precaution  to  in- 
crease the  dose  measurably.  In  badly  infected 
herds  it  should  be  doubled. 

If  serum  is  carefully  administered,  with  due 
precautions  regarding  rapid  absorption,  it  is  prac- 
tically impossible  to  overdose,  and  there  is  no  dis- 
ease or  condition  of  swine,  so  far  as  we  know,  that 
even  an  unnecessarily  large  dose  of  serum  alone 
will  affect  unfavorably.  Thus  in  case  of  suspected 
hog  cholera,  in  which  the  diagnosis  cannot  be 
clearly  established,  it  may,  and  should  be,  admin- 


METHODS    OF   USING   ANTI-HOG-CHOLEfcA   SERUM        133 

istered ;  and  in  case  deviation  from  the  dose  table 
seems  desirable,  a  quantity  unnecessarily  large  is 
preferable  to  one  dangerously  small. 

Therapeutic  value  of  serum  alone.  Serum  is 
employed  almost  entirely  as  a  preventive  of  hog 
cholera,  but  it  possesses  some  therapeutic  value 
when  used  in  generous  doses  early  in  the  course 
of  the  disease.  Herein  lies  the  reason  for  in- 
creased doses  in  badly  infected  herds — many  ani- 
mals apparently  well  are  really  in  the  first  stages 
of  hog  cholera.  Ordinarily  we  do  not  regard 
treating  hogs  visibly  sick  with  cholera  as  a  profit- 
able venture,  but  when  the  disease  appears  in  mild 
form,  or  when  the  animals  are  adults  or  of  excep- 
tional value,  we  are  more  than  repaid  for  our 
efforts  to  save  them.  Double  doses  of  serum  are 
recommended  under  such  circumstances,  and  or- 
dinary doses  may  follow  at  intervals  of  from  three 
to  seven  days,  as  the  condition  of  the  animal  re- 
quires. 

Good  nursing  as  an  adjunct  to  serum  treatment 
is  of  the  utmost  value.  A  plentiful  supply  of  fresh 
water  should  be  furnished,  to  which  may  be  added 
a  saline  purgative  when  there  is  constipation. 
The  diet  should  be  severely  restricted,  and  under 
no  circumstances  should  unconsumed  food  be  kept 
before  the  animal.  Warm  milk  alone  is  an  excel- 
lent diet  for  hogs  suffering  with  cholera. 

Dangers  and  after-effects  of  serum  alone  im- 


134  HOG   CHOLEKA 

munization.  Occasionally  rough  handling  during 
the  process  of  vaccinating  will  injure  an  animal, 
but  this  is  not  to  be  charged  to  the  effect  of  serum. 
Sometimes,  especially  in  very  young  pigs,  a  tem- 
porary stiffness  or  lameness  exists  for  a  day  or 
two  following  treatment,  but  this  is  exceptional, 
and  usually  it  is  of  little  consequence.  Large 
quantities  of  cold  serum,  especially  when  the  dose 
is  not  well  distributed,  sometimes  cause  this 
trouble  in  an  aggravated  form.  The  obvious  pre- 
cautions are  to  use  due  care  in  injecting,  and  to 
warm  serum  that  is  to  be  administered  to  young 
pigs  in  cold  weather.  A  temperature  approaching 
blood  heat  is  desirable,  and  may  be  secured  by 
placing  the  bottles  in  warm  water. 

Very  exceptionally  there  is  observed,  immedi- 
ately following  serum  administration,  a  rapidly 
spreading  local  infection  often  involving  an  entire 
quarter  and  encroaching  on  other  parts.  There 
is  acute  lameness  in  the  affected  quarter.  The 
area  involved  is  either  doughy  in  consistency,  or 
else  gas  formation  is  evident,  and  under  both  con- 
ditions there  is  pronounced  edema.  The  skin 
usually  assumes  a  purple  hue.  As  a  rule,  animals 
thus  affected  die  in  a  short  time.  We  have  seen 
but  a  limited  number  of  such  cases,  and  with  one 
exception,  all  could  be  traced  to  gross  carelessness 
in  technique,  or  to  working  conditions  which  ren- 
dered even  average  technique  impossible.  We 


METHODS    OF   USING  ANTI-HOG-CHOLEKA   SEEUM        135 

have  never  seen  a  considerable  number  of  animals 
in  one  herd  thus  affected. 

Abscesses  follow  serum  administration  infre- 
quently, and  like  the  rapidly  terminating  type  of 
infection  just  described,  they  are  usually  asso- 
ciated with  faulty  technique  or  conditions  below 
the  average  as  far  as  sanitary  surroundings  of 
the  animals  are  concerned.  They  occur  most  fre- 
quently in  poorly  nourished,  weak  animals,  but 
are  not  always  thus  limited,  nor  is  it  possible  in 
all  cases  to  ascribe  them  to  bad  technique.  The 
bacterial  flora  of  the  particular  surroundings  in 
which  the  immunizing  is  done  seems  to  play  an  im- 
portant part,  but  even  this  factor  may  be  con- 
trolled to  a  great  extent  by  the  free  use  of  disin- 
fectant. Dust  contamination  of  serum  and  instru- 
ments also  favors  abscess  formation,  and  for  this 
reason  one  should  work  out  of  doors  whenever 
possible.  Failure  to  distribute  the  dose  of  serum 
thoroughly  sometimes  results  in  local  inflamma- 
tion, leading  to  abscess  formation.  Abscesses  are 
rare  when  the  serum  is  not  contaminated,  when 
care  is  used  in  administering  it,  and  when  the 
treated  animals  are  in  reasonably  clean  quarters. 

Vaccination  abscesses  usually  encapsulate  and 
form  slowly,  and  although  they  sometimes  reach  a 
considerable  size  and  retard  the  growth  of  the 
animal  to  some  extent,  they  rarely  threaten  its 
life  or  cause  general  symptoms  of  disease.  If 


136  HOG    CHOLERA 

they  occur  in  the  hams  of  hogs  ready  for  market 
they  are  highly  objectionable,  as  they  cause  con- 
demnation of  the  entire  quarter  in  which  they  are 
located.  The  handling  of  vaccination  abscesses 
consists  of  opening  them  when  the  first  evidence 
of  fluctuation  appears,  pressing  out  the  thick, 
greenish-yellow  pus  which  they  usually  contain, 
and  irrigating  the  sac  with  weak  antiseptic  solu- 
tion. In  opening,  the  incision  should  be  made  with 
due  regard  for  continuous  drainage. 

Considerable  space  has  been  devoted  to  these 
untoward  results  which  sometimes  follow  serum 
administration,  but  on  the  whole  they  are  uncom- 
mon when  reasonably  good  technique  is  employed. 
One  who  is  careful  will  immunize  hundreds  and 
even  thousands  of  hogs  without  encountering 
difficulties  of  this  kind,  but  it  is  well  to  know  that 
they  sometimes  occur,  and  to  understand  the  im- 
portance of  seemingly  trifling  influences  that 
operate  to  cause  or  prevent  them. 

Summary  of  action  of  serum  alone. 

1.  Produces  in  hogs  not  infected  with  cholera 
near  the  time  of  its  administration  a  passive  im- 
munity lasting  about  four  weeks. 

2.  Produces  active  and  permanent  immunity  in 
swine  more  than  twelve  weeks  old  that  are  defi- 
nitely infected  with  cholera  immediately  before 
immunization,  or  during  the  three  or  four  weeks 
following  it. 


METHODS   OF   USING   ANTI-HOG-CHOLERA   SERUM        137 

3.  Produces  an  active  and  permanent  immunity 
in  many  pigs  less  than  twelve  weeks  old  which  are 
definitely  infected  with  cholera  near  the  time  of 
treatment,  but  cannot  be  depended  on  to  produce 
permanent  immunity  in  all  young  pigs. 

4.  Does  not  affect  other  diseases  unfavorably, 
and  if  it  is  carefully  administered,  untoward  re- 
sults following  its  use  are  practically  negligible. 

Indications  for  serum  alone. 

1.  In  seemingly  well  and  exposed  animals  in  in- 
fected herds. 

2.  In  all  cases  in  which  a  four-week  immunity 
will  meet  the  requirements.     (Show  hogs  under 
some  circumstances,  those  near  the  end  of  the 
fattening   period,   breeding   animals    crated   for 
shipping.) 

3.  In  all  cases  in  which  immediate  protection 
is  required  and  simultaneous  treatment  cannot  be 
safely  administered.    (Sows  near  farrowing  time, 
weak  unthrifty  animals  temporarily  threatened 
with  hog  cholera.)    See  also  follow-up  treatment. 

C ontra-indications  for  serum  alone.  Serum 
alone  is  contra-indicated  when  the  following  con- 
ditions coexist  in  the  same  herd  or  animal. 

1.  A  permanent  immunity  is  desired. 

2.  Hog  cholera  infection  does  not  exist. 

3.  Simultaneous  treatment  may  safely  be  ad- 
ministered. 

Simultaneous     or     double    treatment.      This 


138  HOG   CHOLERA 

method  consists  of  giving  serum  in  exactly  the 
same  manner  as  has  already  been  described,  and 
of  administering  at  the  same  time,  and  with  a 
separate  syringe,  the  required  dose  of  hog  cholera 
virus.  Usually  the  dose  of  serum  is  given  in  one 
of  the  sites  of  injection  already  mentioned,  and 
the  virus  at  the  corresponding  point  on  the  oppo- 
site side.  The  technique  of  administering  virus 
does  not  differ  from  that  employed  with  serum, 
except  that  special  care  is  required  in  disinfecting 
the  site  of  injection  after  the  needle  is  removed. 
Also  the  dose  of  virus  is  so  small  that  massage  is 
not  required.  No  virus  should  be  allowed  to  drop 
on  the  ground,  and  all  that  is  not  used  should  be 
burned. 

Simultaneous  treatment  possesses  the  great  ad- 
vantage of  producing  a  permanent  immunity  in  all 
swine  that  are  more  than  twelve  weeks  old,  and  in 
many  of  those  that  are  younger.  On  the  other 
hand  it  involves  the  use  of  a  lethal  dose  of  hog 
cholera  virus,  thus  producing  certain  sequelae  and 
adding  specific  dangers  that  are  not  associated 
with  serum  alone  treatment. 

Dosage  of  serum  and  virus.  The  same  princi- 
ples that  apply  to  dosage  of  serum  administered 
alone,  apply  when  it  is  given  with  virus.  We  give 
at  least  as  much  serum  as  the  label  indicates,  in- 
creasing the  dose  when  we  are  compelled  to  ad- 
minister simultaneous  treatment  to  hogs  below 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SERUM         139 

average  in  resistance.  In  using  virus  the  label  is 
likewise  our  guide.  Although  in  giving  simultane- 
ous treatment  to  hogs  we  regularly  administer  a 
lethal  dose  of  virus,  we  should  not  let  that  fact 
tempt  us  to  decrease  the  quantity.  Too  much 
stress  has  been  laid  on  carefully  graded  doses  of 
virus  and  on  the  necessity  for  balancing  virus  and 
serum  doses.  One  mil  of  virus  will  kill  almost  as 
regularly  and  quickly  as  three,  and  an  ordinary 
dose  of  serum  will  protect  against  either  quantity. 
The  dose  of  serum  is  not  governed  by  the  quantity 
of  virus,  but  by  the  potency  of  the  serum,  which 
is  reflected  on  the  label,  and  by  the  size  and  con- 
dition of  the  hog.  Thus,  if  circumstances  compel 
us  to  give  simultaneous  treatment  to  hogs  below 
average  in  resistance,  we  increase  the  dose  of 
serum,  but  leave  the  virus  dose  unchanged.  The 
primary  aim  is  to  give  enough  virus  to  infect,  and 
enough  serum  to  protect  against  an  infecting  dose. 
In  our  own  field  work  we  never  give  less  than  one 
mil  of  virus  nor  more  than  two  mils,  our  prefer- 
ence being  for  a  dose  approaching  the  latter  figure 
in  all  swine  weighing  more  than  seventy-five 
pounds. 

After-effects  and  dangers  of  simultaneous  treat- 
ment. A  reaction,  very  slight  in  the  vast  ma- 
jority of  cases,  but  severe  in  others,  usually 
follows  simultaneous  treatment.  In  effect,  the 
animals  go  through  an  attack  of  hog  cholera  which 


140  HOG    CHOLERA 

is  so  light  that  symptoms  do  not  appear,  but  if 
temperatures  are  recorded  the  curve  will  usually 
show  slight  elevation  and  more  or  less  fluctuation 
between  the  fifth  and  twelfth  days  following  immu- 
nization. Under  unfavorable  conditions  the  reac- 
tion becomes  relatively  more  severe,  and  symp- 
toms of  hog  cholera  may  appear.  If  these  are 
slight,  complete  recovery  will  take  place;  if  they 
are  severe,  they  threaten  the  life  of  the  animal; 
and  if  it  dies  its  death  is  due  to  hog  cholera  just 
as  truly  as  it  would  be  if  no  serum  were  adminis- 
tered^.  Sickness  and  deaths  due  to  hog  cholera 
following  simultaneous  treatment  are  termed 
"breaks"  or  "vaccination  cholera."  If  the  trou- 
ble appears  during  the  first  three  weeks  following 
treatment  it  is  called  a  "serum  break"  the  suppo- 
sition being  that  the  serum  is  impotent  and  allows 
the  virus  to  kill  the  animal ;  if  it  appears  after  a 
longer  time  it  is  termed  a  "virus  break, ' '  the  effect 
being  ascribed  to  the  fact  that  inert  virus  has  been 
administered  and  the  serum  produces  only  a  tem- 
porary immunity,  which,  as  it  disappears,  leaves 
the  herd  again  susceptible. 

In  reality, ' '  serum  breaks ' '  are  due  to  a  variety 
of  causes,  among  which  are  impotent  serum, 
faulty  technique  in  vaccinating,  insufficient  doses 
of  serum,  and,  in  addition,  any  influence  whatso- 
ever that  temporarily  lowers  the  resistance  of  the 
animals  during  the  two  or  three  weeks  subsequent 


METHODS   OF   USING   ANTI-HOG-CHOLERA   SERUM        141 

to  vaccination.  Most  important  among  these  may 
be  mentioned  shipping,  weaning,  castrating,  heavy 
ascaris  infestation  in  which  the  gall  ducts  are 
filled  with  the  parasites,  overheating  incident  to 
handling  during  immunization,  severe  exposure  in 
cold  rains  during  the  reaction  period,  injudicious 
feeding  during  that  time,  and  general  unthrifti- 
ness  due  to  any  cause.  These  are  not  imaginary 
influences  that  may  cause  " breaks,"  but  are  real 
influences  that  do  cause  them,  and  while  they  may 
be  repeatedly  ignored  without  dire  consequences, 
the  tendency  is  to  ignore  them  once  too 
often. 

The  practicing  veterinarian  is  helpless  in  re- 
gard to  the  potency  of  the  serum  he  uses.  He  has 
no  opportunity  to  test  it,  and  must  therefore  ac- 
cept it  on  faith.  His  safest  plan  is  to  secure  it 
only  from  the  most  reliable  sources.  Of  course  if 
the  virus  used  is  up  to  standard,  and  the  serum  is 
impotent  the  hogs  that  receive  the  two  simultane- 
ously will  probably  die,  and  no  veterinarian  who 
has  had  this  result  follow  his  work  will  soon  for- 
get it.  It  is  well  to  remember,  though,  that  impo- 
tent serum  is  just  one  of  many  causes  of  so-called 
" serum  breaks"  and  that  the  remainder  of  these 
causes  are  for  the  most  part  controlled  by  the 
practitioner  or  breeder.  There  is  a  triple  respon- 
sibility associated  with  all  simultaneous  treat- 
ment, and  neither  serum  producer,  veterinarian 


142  HOG    CHOLEBA 

nor  breeder  should  throw  stones  until  he  is  sure 
he  is  not  living  in  a  glass  house. 

Shipping  hogs  immediately  after  simultaneous 
treatment  has  been  administered,  or  worse  still, 
holding  them  three  or  four  days  and  then  shipping 
them  so  that  they  will  be  on  the  road  at  the  time 
the  reaction  following  treatment  is  in  progress,  is 
a  fruitful  cause  of  serum  "breaks."  We  are 
aware  that  this  practice  is  stoutly  defended  by 
many,  principally  by  those  who  administer  the 
treatment  in  stockyards,  see  the  hogs  loaded  in 
cars,  and  never  see  them  again.  The  practice  is 
not  defended  by  veterinarians  who  are  on  the  re- 
ceiving end  of  the  line,  for  it  is  a  well-known  fact 
that  "serum  breaks "  often  occur  soon  after  these 
hogs  reach  the  farms  on  which  they  are  to  be 
fattened,  and  it  is  fortunate  indeed  if  hog  cholera 
is  not  thus  transmitted  to  other  herds  in  the  vi- 
cinity. This  method  of  handling  hogs  may  be 
necessary  under  present  conditions,  even  if  it  must 
carry  with  it  the  risks  we  have  mentioned,  but 
granting  that  it  is  necessary,  let  us  at  least  recog- 
nize the  dangers  in  their  true  proportions,  and 
work  toward  a  better  method  of  handling  feeding 
hogs. 

Lowered  resistance  due  to  shipping  accounts 
for  many  of  these  "breaks,"  yet  the  tendency  is 
to  charge  them  to  impotent  serum.  The  best  se- 
rum that  can  be  manufactured  will  not  protect  all 


METHODS    OF   USING   A  NTI- HOG- CHOLERA   SERUM        143 

animals  thus  handled,  but  the  fact  that  many  lots 
of  hogs  will  endure  it,  leads  some  to  think  that  all 
ought  to  do  so.  Individual  differences  exist,  and 
while  they  are  not  always  obvious,  the  lots  that 
"break"  more  often  consist  of  hogs  that  have 
been  held  in  stockyards  a  long  time,  those  badly 
infested  with  parasites,  or  suffering  with  respira- 
tory diseases.  Distances  traveled  to  and  from  the 
stockyards,  and  the  degree  of  crowding  of  the  cars 
are  also  potent  factors  in  determining  the  hazards 
of  shipping  simultaneously  treated  hogs. 

Hogs  are  not  fit  subjects  for  simultaneous  treat- 
ment just  as  they  are  unloaded  from  long  railway 
journeys.  It  is  best  to  give  these  animals  serum 
alone  at  this  time,  and  simultaneous  treatment 
two  or  three  weeks  later.  This  is  the  follow-up 
treatment  which  we  have  already  mentioned, 
and  which  will  be  considered  separately  in  this 
chapter. 

In  farm  hogs,  weaning,  castrating,  ringing,  and 
the  absurd  practice  of  knocking  "black  teeth"  out 
of  all  pigs  may  operate  individually  or  collec- 
tively to  lower  resistance  and  render  simultaneous 
treatment  dangerous.  Due  to  pressure  of  other 
work  pigs  are  frequently  neglected  several  weeks, 
then  suddenly  there  is  a  desire  to  do  all  of  these 
things,  and  immunize,  at  the  same  time,  in  order 
to  avoid  handling  the  animals  more  than  once. 
The  wonder  is  that  pigs  will  frequently,  even  usu- 


144  HOG    CHOLERA 

ally,  survive  the  ordeal,  but  exceptions  prove  the 
rule — and  embarrass  the  veterinarian.  In  several 
instances  we  have  known  men  to  castrate  pigs  dur- 
ing the  week  following  simultaneous  treatment. 
In  some  of  these  a  number  of  the  castrated  pigs 
died,  while  the  female  pigs,  which  remained  as 
checks,  survived,  thus  furnishing  excellent  but 
rather  involuntary  and  costly  experiments.  Pigs 
are  best  castrated  as  sucklings,  but  in  any  event, 
it  is  well  to  separate  castrating  and  simultaneous 
treatment  at  least  two  or  three  weeks. 

Ascarids  may  exist  in  the  intestine  in  large 
numbers  without  appreciably  lowering  the  resist- 
ance of  simultaneously  treated  pigs,  but  if  the 
parasites  enter  and  occlude  the  gall  duct,  the  in- 
fested hog  shows  a  remarkable  intolerance  for 
virus.  We  have  observed  this  intolerance  again 
and  again  both  in  test  pigs  and  in  the  field.  Prac- 
titioners cannot  always  avoid  trouble  due  to  as- 
carids,  for  granting  that  they  know  the  parasites 
exist  in  a  herd,  it  is  not  always  possible  to  deter- 
mine their  location  in  the  individual,  and  often 
it  is  not  safe  to  delay  treatment.  Severe  jaundice 
in  pigs  is  usually  due  to  ascarids  in  the  gall-duct, 
and  its  presence,  easily  observed  in  white  pigs, 
should  suggest  caution. 

Overfeeding  is  injurious  to  pigs  passing  through 
the  reaction  following  simultaneous  treatment. 
Any  one  who  has  observed  serum  tests  knows 


METHODS   OF   USING   ANTI-HOG-CHOLERA   SERUM        145 

that.  Often  there  is  no  change  in  the  appetite 
during  this  time,  but  if  a  few  animals  in  a  lot  eat 
scantily,  the  others  gorge  themselves  on  the  sur- 
plus thus  rendered  available,  and  a  period  of  dis- 
tress or  dullness  follows,  during  which  the  virus 
may  get  in  its  work.  A  simple  rule  is  to  feed  so 
that  the  animals  remain  just  a  little  hungry  after 
each  meal,  and  to  be  prepared  for  a  slight  lagging 
in  appetite  between  the  fifth  and  twelfth  days  fol- 
lowing treatment. 

Methods  of  preventing  ' i  serum  breaks ' '  are  ob- 
vious when  the  causes  of  these  "  breaks "  are  un- 
derstood. Full  doses  of  potent  serum  adminis- 
tered with  due  regard  for  rapid  absorption,  and 
proper  caution  in  regard  to  treating  hogs  below 
average  in  resistance  are  the  two  essential  con- 
siderations. 

Handling  "serum  breaks"  involves  first  of  all 
informing  the  owner  of  the  animals,  before  serum 
is  administered,  that  such  "breaks"  are  possible 
but  by  no  means  probable,  and  asking  him  to  ob- 
serve the  herd  carefully  and  report  any  sickness 
that  may  appear  during  the  three  weeks  following 
treatment.  Should  a  "break"  occur  prompt 
measures  are  required.  If  only  two  or  three  hogs 
out  of  a  herd  of  considerable  size  appear  dull,  and 
if  these  have  sickened  later  than  the  twelfth  or 
fourteenth  day  following  vaccination,  it  is  well  to 
take  temperatures  on  several  animals  in  the  herd. 


146  HOG    CHOLEEA 

If  the  temperatures  vary  between  normal  and  a 
little  above  104°  F.  and  if  there  is  no  visible  dull- 
ness, serum  alone  may  be  given  to  the  sick  ani- 
mals only;  but  if  sickness  appears  before  the 
tenth  day,  if  several  hogs  are  dull,  or  if  a  number 
of  them  show  temperatures  near  106°  F.  the  entire 
herd  should  receive  full  doses  of  serum  alone 
without  delay.  Most  "breaks,"  taken  in  time,  can 
be  checked. 

Abortion  in  sows  has  been  caused  by  simultane- 
ous treatment,  but  it  is  rather  unusual,  and  occurs 
most  frequently  during  "breaks"  due  to  the 
causes  we  have  mentioned.  Sows  near  farrowing 
time  certainly  should  not  receive  serum  and  virus, 
but  when  they  are  in  the  early  period  of  gestation 
we  are  frequently  compelled  to  assume  the  slight 
risks  as  a  necessary  evil. 

Stunting  may  result  from  simultaneous  treat- 
ment, and  we  are  told  that  one  of  America 's  most 
famous  pure-bred  breeders  had  his  herd  ruined  by 
unthriftiness  following  vaccination.  We  do  not 
know  the  particulars,  but  we  do  know  that  such 
consequences  need  not  follow  simultaneous  treat- 
ment judiciously  administered,  and  we  know  that 
hundreds  of  pure-bred  breeders  maintain  fine 
herds  immune,  and  are  satisfied.  We  have  al- 
ready enumerated  a  few  of  the  factors  which  cause 
"breaks."  Any  one  of  these  may  cause  death,  or 
falling  just  short  of  such  a  result,  stunt  the  ani- 


METHODS    OF    USING    ANTI-HOG-CHOLERA   SEKUM         147 

mal.    Thus  it  is  the  abuse  of  simultaneous  treat- 
ment rather  than  its  use  which  incriminates  it. 

Elimination  of  hog  cholera  virus  in  the  excre- 
tions of  simultaneously  treated  pigs  sometimes 
takes  place  for  a  few  days  during  the  resulting 
reaction.     There  was  a  time  when  this  fact  was 
denied,  but  no  person  experienced  in  handling  hog 
cholera  would  seriously  question  it  to-day.    Beac- 
tions  vary  between  one  extreme  in  which  no  tem- 
perature   elevation   is   recorded,   and   the    other 
rather  unusual  one  in  which  death  takes  place.    In 
the  first  instance  virus  elimination  is  rare,  but  as 
the  latter  extreme  is  approached,  it  is  the  rule. 
Most  hogs  do  not  eliminate  infectious  material, 
but  the  exceptions  to  the  rule  are  so  numerous  that 
it  is  not  safe  to  keep  susceptible  animals  with 
those  that  receive  simultaneous  treatment. 

Because  of  the  danger  of  virus  elimination,  a 
period  of  quarantine  is  usually  imposed  on  simul- 
taneously treated  hogs.  The  duration  of  this 
quarantine  is  prescribed  by  law  in  most  states,  the 
usual  time  varying  between  twenty-one  and  thirty 
days,  with  extension  in  case  "vaccination  chol- 
era" appears.  Hogs  that  have  shown  no  physical 
evidence  of  disease  are  very  rarely  eliminating 
virus  at  the  end  of  twenty-one  days  following 
serum- virus  immunization. 

"  Virus  breaks "  are  not  manifest  until  several 
weeks  following  simultaneous  treatment,  and  they 


148  HOG    CHOLEKA 

are  due  to  inert  virus,  insufficient  doses,  and,  very 
probably,   to   giving   simultaneous   treatment  to 
pigs  too  young.    If  virus  is  inert  infection  is  not 
produced,  active  immunity  is  not  established,  and 
if  hogs  chance  to  be  exposed  to  cholera  after  the 
passive  immunity  due  to  the  serum  has  disap- 
peared, they  readily  contract  the  disease.     If  a 
pig  more  than  twelve  weeks  old  receives  a  full 
dose  of  virulent  virus  as  a  part  of  simultaneous 
treatment  and  remains  well  during  the  following 
four  weeks,  his  immunity  to  cholera  may  be  ac- 
cepted as  a  fact ;  if  a  herd  that  is  given  simultane- 
ous treatment  passes  the  first  four  weeks  without 
incident  and  later  "  breaks "  with  hog  cholera,  we 
may  safely  assume  that  inert  virus  was  used,  or 
that  doses  ridiculously  low  were   administered. 
Sometimes  inert  virus  is  sent  out  with  impotent 
serum  that  will  protect  against  no  other  kind; 
sometimes   virus   is   used   too   long   after  being 
drawn;  and  if  it  is  heated — we  do  not  believe  it 
should  be — there  is  some  danger  of  killing  it. 

Prevention  of  " virus  breaks,"  when  one  under- 
stands their  causes,  is  simple.  Provided  one 
treats  pigs  more  than  twelve  weeks  old,  a  full  dose 
of  virulent  virus  in  conjunction  with  the  serum 
used  in  simultaneous  treatment  is  all  that  is  re- 
quired. A  breeder  who  is  familiar  with  the  bene- 
fits and  hazards  of  simultaneous  treatment  will 
not  be  greatly  disturbed  if  a  shoat  or  two  should 


METHODS    OF    USING    ANTI-HOG-CHOLERA   SEBUM        149 

die  of  "vaccination  cholera "  when  he  has  his  herd 
immunized;  he  may  even  view  a  more  serious 
"serum  break "  complacently,  but  if  his  swine  re- 
ceive simultaneous  treatment  as  shoats  and  die  of 
hog  cholera  when  they  are  about  ready  for  market, 
he  has  a  real  grievance,  which  he  will  be  slow  to 
forget.  It  is  fully  as  important  that  virus  shall  be 
virulent  as  it  is  that  serum  shall  be  potent. 

"Hemorrhagic  septicemia"  forms  a  convenient 
and  altogether  too  common  alibi  for  both  ' '  serum 
breaks "  and  "virus  breaks."     If  either  occurs 
(and  disease  which  is  really  hog  cholera  is  called 
"hemorrhagic   septicemia"),    this    automatically 
absolves  from  all  blame  the  serum  producer  who 
sells  impotent  serum  or  inert  virus ;  it  excuses  the 
man  who  abuses  the  products  in  administering 
them,  as  well  as  the  breeder  who  subjects  his  ani- 
mals to  improper  care  during  the  resulting  reac- 
tion.   The  only  defect  in  such  an  alibi  is  that  it 
does  not  save  the  hogs  or  tell  us  what  really  kills 
them.    When  hogs  kept  under  average  farm  con- 
ditions receive  simultaneous  treatment  and  any 
considerable  number  of  them  develop  febrile  dis- 
ease during  the  following  three  weeks,  unless  a 
cause  other  than  "hemorrhagic  septicemia"  is 
obvious  the  chances  are  ten  to  one  that  the  primary 
cause  of  the  disease  is  hog  cholera  virus.    Under 
such  conditions  no  other  cause  can  be  accepted 
unless  negative  filtration  experiments,  requiring 


150  HOG    CHOLERA 

about  ten  days,  are  carried  out.  The  field  man 
who  represents  a  laboratory  which  sells  question- 
able serum,  and  who  pronounces  such  " breaks" 
"hemorrhagic  septicemia"  on  information  ob- 
tained from  a  few  autopsies  or  a  brief  bacterio- 
logical examination,  must,  in  mercy,  be  called 
ignorant,  or  else  his  honesty  must  be  questioned. 
Most  "breaks"  can  be  prevented,  but  some  cannot. 
Let  us  prevent  those  we  can,  and  call  the  others 
hog  cholera.  That  is  what  they  are. 

Under  conditions  existing  in  the  United  States 
during  the  last  decade  simultaneous  treatment  has 
been  a  great  boon  to  the  swine  industry;  it  has 
saved  hogs  worth  millions  of  dollars ;  it  has  made 
it  possible  for  any  breeder  who  will,  to  banish  fear 
that  hog  cholera  will  destroy  his  herd.  But  in 
spite  of  these  facts  it  is  not  perfect  in  its  opera- 
tion; it  is  sometimes  instrumental  in  spreading 
the  disease  it  is  intended  to  check ;  it  involves  some 
dangers.  These  are  best  avoided  when  their 
causes  are  fully  understood ;  best  combated  when 
they  are  frankly  admitted  to  exist. 

Forewarned  is  forearmed.  Any  veterinarian 
who  contemplates  using  simultaneous  treatment 
in  a  client's  herd  should  tell  him  that  it  involves 
a  little  danger;  that  the  herd  must  be  carefully 
handled  for  about  three  weeks;  that  if  a  " break" 
should  occur  it  must  be  reported  promptly,  and 
that  under  no  circumstances  are  susceptible  hogs 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SERUM        151 

to  come  in  contact  with  vaccinated  ones  during 
the  four  weeks  following  treatment.  It  is  some- 
times difficult  to  mention  these  things,  without 
causing  the  dangers  to  be  exaggerated  in  a  client 's 
mind,  and  some  breeders  will  decide  not  to  take 
risks  which  they  would  readily  assume  could  they 
know  how  slight  they  really  are.  Nevertheless  a 
veterinarian's  first  duty  is  to  protect  his  client, 
and  he  must  protect  himself  if  he  is  to  remain  in 
practice.  The  man  who  glibly  advises  that  there 
is  "no  danger "  following  his  vaccinating  is  not 
doing  either. 
Summary  of  action  of  simultaneous  treatment. 

1.  Produces  an  active  permanent  immunity  in 
all  hogs  more  than  twelve  weeks  of  age. 

2.  Produces  active  immunity  in  some  suckling 
pigs,  passive  immunity  in  others. 

3.  Usually  produces  a  very  mild  reaction  begin- 
ning about  five  days  following  treatment,  and  last- 
ing less  than  seven  days. 

4.  In  hogs  with  low  resistance,1  sometimes  pro- 
duces a  severe  reaction  which  exceptionally  ter- 
minates in  death. 

5.  Causes  some  hogs  to  eliminate  hog  cholera 
virus  in  their  excretions  during  the  time  the  reac- 
tion is  in  progress. 

1  The  terms  ' '  resistance ' '  and  ' '  condition ' '  should  not  be  con- 
fused. The  former,  as  used  here,  applies  to  the  state  of  the  ani- 
mal's natural  defenses  against  disease,  and  is  determined  by  the 
history,  as  well  as  by  the  appearance  of  the  animal.  "Condition" 


152  HOG   CHOLEEA 

6.  May  cause  abortion  in  pregnant  sows,  and 
may  stunt  pigs  if  they  are  treated  while  their  re- 
sistance is  low. 

Simultaneous  treatment  is  indicated  in  herds 
where  hog  cholera  virus  is  almost  sure  to  find  its 
way  sooner  or  later,  but  where  actual  infection  of 
the  herd  may  be  delayed  several  weeks  or  months. 
Such  conditions  exist: 

1.  In  sound  herds  on  infected  farms. 

2.  In  other  herds  immediately  threatened  with 
cholera. 

3.  In  some  show  hogs.     See  "  handling  show 
hogs"  in  Chapter  IX. 

4.  On  farms  on  which  hog  cholera  has  appeared 
periodically. 

5.  In  very  large  herds  in  which  there  is  con- 
stant exchange  of  animals. 

6.  In  garbage-fed  herds. 

Simultaneous  treatment  is  contra-indicated: 

1.  When  it  cannot  be  applied  by  experienced 
men. 

2.  When  the  entire  herd  cannot  be  immunized. 
(Some  may,  if  necessary,  receive  serum  alone,  but 
none  must  be  left  susceptible.) 

applies  more  specifically  to  the  degree  and  quality  of  flesh  an 
animal  carries,  as  well  as  to  the  appearance  of  the  coat,  and  is 
determined,  in  hogs,  principally  by  inspection.  Fat  hogs  recently 
shipped  or  fat  sows  that  have  recently  farrowed,  though  in  good 
condition,  will  not  tolerate  simultaneous  treatment  nearly  as  well 
as  ordinary  farm  hogs  in  very  moderate  flesh.  The  ' '  resistance ' ' 
of  the  latter  is  higher,  although  their  "  condition ' '  is  lower. 


METHODS   OF   USING   ANTI-HOG-CHOLERA   SEBUM        153 

3.  When  the  treated  herd  cannot  be  properly 
segregated. 

4.  For  sucking  pigs  as  a  routine  measure.    (In- 
formation still  incomplete  on  this  point.) 

5.  For  sows  about  to  farrow,  or  for  those  nurs- 
ing young  litters. 

6.  In  badly  infected  herds. 

7.  In  animals  with  low  resistance  due  to  ship- 
ping, weaning,  castrating  and  other  influences. 

8.  In  all  circumstances  in  which  serum  alone 
will  be  equally  effective. 

Follow-up  treatment.  This  consists  of  giving 
serum  alone  and  following  it  in  a  few  weeks,  usu- 
ally less  than  four,  with  simultaneous  treatment. 
It  has  been  called  "double  treatment "  by  some, 
but  according  to  usage  which  has  now  become 
fixed,  the  terms  " double  treatment"  and  "simul- 
taneous treatment "  are  applied  interchangeably 
to  serum-virus  administration.  It  therefore  seems 
desirable  to  apply  to  serum  alone  followed  by 
simultaneous  treatment,  the  separate,  distinct  and 
self-explanatory  term,  "follow-up  treatment. " 

Follow-up  vaccination  is  safer  than  simultane- 
ous treatment,  it  can  be  applied  under  circum- 
stances which  practically  forbid  the  use  of  the 
latter  method,  and  the  final  result  is  the  same — 
a  permanent  immunity  is  established.  There  are 
those  who  believe  that  the  passive  immunity  pro- 
duced by  the  dose  of  serum  alone  prevents  the  re- 


154  HOG    CHOLERA 

action  and  consequent  permanent  immunity  due 
to  subsequent  serum-virus  treatment.  The  im- 
pression seems  to  prevail  that  there  is  just  one 
way  to  immunize  a  hog  permanently,  and  that  is 
to  give  him  simultaneous  treatment  as  a  first  and 
only  measure.  Various  troubles  following  follow- 
up  treatment  have  been  cited  as  proof  of  this 
theory,  but  we  have  never  investigated  a  case  in 
which  there  was  the  least  evidence  that  the  system 
was  fundamentally  at  fault.  The  trouble  has  been 
in  its  application. 

In  applying  the  follow-up  system,  there  is  a 
marked  tendency  for  the  veterinarian  to  give  the 
dose  of  serum  alone  and  to  neglect  for  too  long  a 
time  to  follow  it  with  simultaneous  treatment. 
There  is  no  danger  in  this  unless  the  pigs  happen 
to  be  exposed  to  cholera  after  the  passive  immu- 
nity due  to  the  dose  of  serum  has  disappeared, 
but  too  often  just  that  very  thing  takes  place.  The 
owner  of  the  animals  derives  a  false  sense  of  se- 
curity from  the  fact  that  serum  has  been  adminis- 
tered, and  hence  does  not  report  the  sickness  as 
promptly  as  he  otherwise  would.  The  final  result 
is  that  when  hog  cholera  is  well  started  in  the 
herd,  the  veterinarian  receives  an  urgent  call  to 
give  serum  and  virus  as  the  final  installment  of 
the  follow-up  treatment.  Heavy  losses  inevitably 
follow,  and  the  entire  system  is  condemned.  It 
should  always  be  remembered  that  serum  alone 


METHODS   OF   USING   ANTI-HOG-CHOLERA   SERUM        155 

cannot  be  depended  on  to  protect  more  than  four 
weeks. 

' ' Virus  breaks"  are  no  more  likely  to  occur 
when  follow-up  treatment  is  administered  than 
they  are  following  simultaneous  treatment,  and, 
as  with  the  latter  method,  their  prevention  con- 
sists wholly  of  giving  full  doses  of  virulent  virus, 
and  using  due  care  not  to  treat  pigs  too  young. 
When  these  precautions  are  observed,  we  can 
vouch  for  the  fact  that  follow-up  treatment  pro- 
duces a  permanent  immunity.  We  have  used  it 
since  1912  in  maintaining  many  immune  herds, 
usually  administering  the  final  dose,  simultaneous 
treatment,  when  the  pigs  were  about  twelve  weeks 
old.  We  have  not  had  a  " virus  break"  during 
the  nine  years  the  system  has  been  employed; 
that  is,  no  pigs  that  survived  the  immediate  reac- 
tion following  the  final  serum-virus  treatment  sub- 
sequently developed  hog  cholera.  It  is  our  custom 
to  select  hypers  from  these  herds,  and  so  far  none 
of  them  have  developed  hog  cholera  as  a  result 
of  hyperimmunization.  In  the  East  many  veteri- 
narians use  the  follow-up  system  in  maintaining 
herds  immune  to  cholera,  and  " virus  breaks"  are 
not  common. 

Experimentally  we  have  tested  the  effects  of 
giving  follow-up  treatment  using  various  inter- 
vals between  the  time  of  administering  serum 
alone  and  that  of  administering  serum  and  virus, 


156  HOG    CHOLERA 

and  trying  to  smother  the  action  of  virus  by  large 
and  repeated  doses  of  serum  alone  previous  to 
simultaneous  treatment.  In  no  case  have  we  ob- 
tained evidence  to  justify  even  a  suspicion  that 
follow-up  treatment  does  not  produce  permanent 
immunity,  and  we  know  of  no  experimental  work 
that  contradicts  these  results. 

The  factor  of  greater  safety  cannot  well  be 
questioned,  although  it  is  seldom  that  hogs  with 
average  resistance  require  follow-up  treatment. 
Simultaneous  immunization  produces  the  same  re- 
sult, and  is  cheaper.  But  if  exceedingly  valuable 
animals  are  to  be  immunized,  one  cannot  go  amiss 
in  giving  a  dose  of  serum  alone  and  following  it 
in  a  week  or  two  with  simultaneous  treatment.  If 
the  first  dose  of  serum  is  in  the  system,  already 
absorbed,  when  the  second  dose  is  given  with 
virus,  there  can  be  no  question  that  the  hazards 
are  reduced.  Exact  comparisons  of  the  safety  of 
simultaneous  and  follow-up  treatment  are  difficult 
to  make,  because  under  ordinary  conditions  both 
are  nearly  100  per  cent  effective.  We  have  seen 
follow-up  treatment  used  in  immunizing  cattle 
against  rinderpest  with  losses  running  less  than 
5  per  cent  when  simultaneous  treatment  with  the 
same  serum  and  virus  caused  such  heavy  losses  as 
to  forbid  its  use  altogether.  We  do  not  care  to 
generalize  too  far  on  this  point,  but  the  princi- 
ples employed  in  preparing  and  using  the  two  se- 


METHODS    OF    USING   ANTI-HOG-CHOLERA   SERUM         157 

rums  are  the  same,  and  we  offer  the  observation 
for  what  it  is  worth. 
Follow-up  treatment  is  indicated: 

1.  For  very  valuable  hogs  where  the  greatest 
possible  safety  is  required. 

2.  When  the  following  conditions  coexist  in  the 
same  animal  or  herd : 

A.  Immediate  protection  is  imperative. 

B.  Ultimate  permanent  immunity  is  desired. 

C.  Conditions  render  immediate  simultaneous 
treatment  dangerous. 

Follow-up  treatment  is  contra-indicated  in  all 
cases  in  which  it  appears  'that  serum  alone  or  si- 
multaneous treatment  will  be  equally  effective. 

It  is  in  immunizing  hogs  with  resistance  obvi- 
ously below  normal,  and  in  maintaining  immune 
herds  under  somewhat  adverse  conditions  that 
follow-up  treatment  renders  greatest  service.  In 
practice,  especially  in  the  East,  we  constantly  en- 
counter the  three  conditions  we  have  enumerated 
above,  and  follow-up  immunization  relieves  us 
from  the  necessity  of  choosing  between  serum 
alone  which  will  not  produce  a  permanent  immu- 
nity, and  simultaneous  treatment  which  is  posi- 
tively dangerous  at  the  time  when  immediate  pro- 
tection is  required.  In  a  succeeding  chapter  the 
adaptations  of  follow-up  treatment  will  receive 
further  attention  in  connection  with  specific  con- 
ditions which  we  meet  in  the  field. 


CHAPTER  IX 

HANDLING    HOG    CHOLERA   IN    THE   FIELD 

HANDLING  hog  cholera  in  the  field  requires  ap- 
plication of  the  principles  that  have  been  outlined 
in  preceding  chapters.  In  this  chapter  our  plan 
is  to  assume  the  existence  of  certain  actual  con- 
ditions which  the  practitioner  frequently  meets 
in  the  field,  and  to  suggest  methods  of  handling 
suited  to  these  conditions.  "We  know  that  in  doing 
this  we  may  invite  criticism,  for  methods  of  han- 
dling hogs  are  so  widely  different  in  various  parts 
of  the  country  that  one  cannot  supply  details  that 
will  apply  everywhere. 

In  some  parts  of  the  South,  for  instance,  where 
hogs  are  allowed  almost  unlimited  range,  where 
predatory  animals  are  common,  where  hog  cholera 
is  prevalent,  and  where  a  few  breeders  use  simul- 
taneous treatment  regularly,  others  must  protect 
their  hogs  in  the  same  manner,  or  lose  them.  In 
certain  sections  of  the  corn-belt  hog  cholera  is 
prevalent  to  such  a  degree  that  it  is  the  part  of 
wisdom  for  practically  all  breeders  to  maintain 
immune  herds.  In  the  East,  where  hogs  are  rather 
closely  confined,  where  they  are  raised  in  limited 

158 


HANDLING   HOG   CHOLEEA   IN    THE   FIELD        159 

numbers,  where  hog  cholera  is  not  common  and 
its  spread  is  not  rapid,  most  herds  do  not  require 
immunization.  Moreover,  in  the  corn-belt  where 
hog  raising  is  a  business,  methods  of  swine  hus- 
bandry are  relatively  much  better  than  they  are 
in  sections  in  which  it  is  a  mere  adjunct  to 
other  farming  operations.  The  average  corn-belt 
breeder  has  had  more  or  less  experience  with  hog 
cholera,  he  knows  what  it  means  to  have  it  sweep 
unchecked  through  his  herd,  and  he  is  not  in- 
clined to  be  dissatisfied  with  measures  that  will 
check  it,  even  though  these  measures  may  not 
always  be  perfect  in  their  operation.  On  the  other 
hand,  the  Eastern  breeder  whose  herd  we  are 
called  on  to  handle  very  often  is  having  his  first 
experience  with  the  disease,  he  is  inclined  to  be 
skeptical  as  to  the  merits  of  protective  serum,  and 
to  doubt  its  value  if  he  loses  a  few  animals  after  it 
has  been  administered.  Frequently  also,  the  herd 
is  found  in  unthrifty  condition  due  to  poor  meth- 
ods of  swine  husbandry  and  heavy  parasitic  in- 
festation. Virus  cannot  be  used  as  freely  in  such 
surroundings  as  it  can  under  circumstances  where 
its  effects  will  be  more  correctly  judged. 

Despite  these  differences,  though,  and  despite 
the  fact  that  methods  of  swine  husbandry  have  a 
direct  and  important  bearing  on  the  handling  of 
disease,  the  principle  holds  that  hog  cholera  is 
hog  cholera  the  country  over,  and  not,  as  some 


160  HOG   CHOLERA 

would  have  us  believe,  different  according  to  the 
section  of  the  country  in  which  we  chance  to  find 
it.  The  differences  we  observe  in  various  parts  of 
the  country  are  due  principally  to  prevailing  sec- 
ondary invaders,  as  well  as  to  variation  in  viru- 
lence of  the  hog  cholera  virus  itself,  for  they  are 
observed  also  in  comparing  individual  herds  or 
outbreaks  in  any  one  section. 

While  we  must  accept  all  these  variations  and 
allow  for  them,  the  underlying  principles  em- 
ployed in  handling  hog  cholera  remain  unchanged, 
and  it  is  desirable  and  necessary  in  a  treatise  of 
this  kind  to  suggest  definite  working  plans,  leaving 
the  reader  to  alter  or  supply  detail  as  individual 
cases  warrant.  We  are  moved  to  do  this  because 
we  have  seen  young  graduates  of  veterinary  col- 
leges who  had  had  good  instruction  and  whose 
technique  in  administering  serum  left  little  to  be 
desired — we  have  seen  some  of  these  men  practi- 
cally helpless  in  the  presence  of  outbreaks  of 
cholera  which  presented  disturbing  but  not  un- 
usual features.  Likewise  men  who  are  accus- 
tomed to  the  routine  of  vaccinating  thousands  of 
stockyard  hogs  are  sometimes  confused  when  they 
are  called  on  to  accept  the  conditions  they  meet 
on  the  average  farm,  to  prescribe  treatment  for 
a  mixed  lot  of  swine,  and  guide  the  breeder  away 
from  future  trouble.  Mere  knowledge  of  how  to 
vaccinate  hogs  does  not  equip  one  to  handle  hog 


HANDLING   HOG   CHOLERA   IN    THE   FIELD        161 

cholera;  diagnosis,  when  and  whether  to  vacci- 
nate, the  method  to  use,  and  the  subsequent  han- 
dling of  the  herd  all  enter  into  the  problem. 

Handling  .the  cholera  infected  herd.  Let  us 
assume,  as  a  working  basis,  that  a  herd  consisting 
originally  of  one  hundred  ordinary  shoats,  in  good 
condition,  is  infected  with  hog  cholera;  ten  have 
died,  ten  are  visibly  sick,  and  there  is  no  evidence 
of  secondary  infection;  there  are  no  other  hogs 
on  the  farm,  and  the  shoats  are  in  a  pasture  con- 
taining several  acres;  the  owner  has  had  hog 
cholera  in  his  herd  in  previous  years,  and  knows 
the  results  that  may  reasonably  be  expected  from 
preventive  measures.  This  represents  the  sim- 
plest situation  we  are  called  on  to  cope  with  in 
handling  hog  cholera  in  the  field. 

Three  methods  of  handling  are  open  to  us : 

1.  Give  generous  doses  of  serum  alone  to  all 
animals  that  are  not  exceedingly  weak. 

2.  Give  simultaneous  treatment  to  all  seemingly 
well  animals,  and  double  doses  of  serum  alone  to 
those  that  are  visibly  sick,  and  not  obviously  near 
death. 

3.  Give  serum  alone  in  full  doses  to  all  ani- 
mals that  are  apparently  well,  in  double  doses  to 
those  that  are  sick  and  have  a  chance  to  recover, 
and  follow  this  in  three  weeks  with  simultaneous 
treatment  for  all  animals  that  were  not  visibly 
sick  at  the  time  of  the  first  treatment.    In  other 


162  HOG    CHOLERA 

words,  give  serum  alone  to  the  sick  animals,  fol- 
low-up treatment  to  those  that  are  apparently 
well. 

Regardless  of  the  method  selected,  we  must 
proceed  promptly  with  the  one  that  becomes  our 
final  choice,  and  we  must  take  immediate  precau- 
tions to  prevent  spread  of  the  disease  to  other 
herds. 

Method  number  one  may  prove  highly  satisfac- 
tory in  some  cases  of  this  kind,  but  it  is  open  to 
the  serious  objection  that  it  may  not  produce  per- 
manent immunity  in  all  the  animals.  In  the  indi- 
vidual, serum  alone  plus  hog  cholera  infection 
produces  permanent  immunity,  but  in  a  herd  of 
this  kind,  although  all  the  animals  are  exposed, 
some  may  not  become  infected  in  time  to  secure 
this  result,  because  hog  cholera  does  not  always 
spread  rapidly  through  herds  that  are  at  pasture 
or  in  other  large  runs. 

Let  us  select,  as  an  instance,  one  shoat  in  the 
herd  and  assume  that  the  animal  has  received 
serum  alone  to-day.  If  in  the  course  of  the  next 
three  or  four  weeks — the  usual  duration  of  immu- 
nity due  to  serum  alone — it  chances  to  take  up 
virus  sufficient  to  infect,  it  will  undergo  a  reaction 
and  thereafter  be  permanently  immune  to  hog 
cholera ;  but  if  the  event  of  infection  is  delayed 
much  longer,  it  will  find  the  animal  susceptible  to 
the  disease.  In  other  words,  if  infection  takes 


HANDLING   HOG    CHOLERA   IN    THE    FIELD         163 

place  while  passive  immunity  due  to  serum  alone 
still  exists,  a  permanent  immunity  is  acquired; 
if  it  takes  place  after  the  passive  immunity  dis- 
appears, the  animal  will  readily  contract  hog 
cholera;  and,  except  where  hogs  are  quite  closely 
confined,  chance  alone  must  decide  whether  any 
particular  individual  will  become  permanently  im- 
mune, or,  failing  in  this,  eventually  die  of  hog 
cholera. 

Method  number  two  will  produce  more  reliable 
results.  The  sick  are  distinguished  from  the  well 
by  physical  appearance  and  temperature  read- 
ings. In  handling  herds  in  this  manner  it  is  our 
custom  to  give  serum  alone  to  all  animals  showing 
temperatures  above  104°  F.,  and  to  all  visibly  sick, 
and  not  at  the  point  of  death,  regardless  of  tem- 
perature reading.  If,  however,  the  weather  is 
warm,  and  if  the  hogs  are  excited  in  handling, 
most  temperatures  will  rise  above  this  point,  and 
the  thermometer  gives  us  very  little  information. 
Under  such  circumstances  physical  appearance  is 
our  only  guide.  A  useful  practice,  whenever  con- 
ditions are  such  that  it  can  be  employed,  is  to  feed 
the  hogs  a  little  grain  and  to  place  those  that  leave 
the  feed  in  a  few  moments  among  the  sick  that  are 
to  receive  serum  alone,  and  those  that  remain  for 
a  longer  time  and  eat  greedily,  among  the  well 
that  are  to  receive  serum  and  virus.  Practically 
all  will  eat  a  little,  but  the  infected  animals  are 


164  HOG    CHOLERA 

first  to  leave  their  feed.  Any  method  of  distin- 
guishing the  sick  from  the  well  is  only  approxi- 
mately correct,  but  a  herd  handled  in  the  manner 
we  have  outlined  will  emerge  from  the  treatment 
permanently  immune  to  hog  cholera.  On  the 
whole,  this  method  of  handling  is  quite  satisfac- 
tory, but  it  is  open  to  the  objection  that  we  may 
introduce  a  more  virulent  strain  of  virus  into 
herds  already  infected,  and  we  may  be  accused  of 
killing  animals  when  we  have  merely  failed  to  pre- 
vent their  death. 

This  method  is  practicable  only  when  the  owner 
of  the  animals  fully  realizes  that  some  apparently 
well  hogs  in  infected  herds  will  die  following  even 
serum  alone  administration,  and  when  he  is  dis- 
posed to  expect  like  losses  following  serum-virus 
treatment.  Veterinarians  experienced  in  handling 
hog  cholera  dread  to  use  virus  in  infected  herds, 
but  we  meet  conditions  under  which  it  is  wise  to 
do  so. 

Method  number  three  is  safest,  and,  as  with 
method  number  two,  the  herd  emerges  with  all 
animals  permanently  immune  to  hog  cholera.  The 
added  expense  is  the  only  objection,  but  in  many 
instances,  especially  when  the  animals  are  above 
average  in  value,  it  is  more  than  justified.  There 
is  great  satisfaction  to  the  practitioner,  as  well  as 
to  the  breeder,  in  knowing  that  nothing  has  been 


HANDLING   HOG   CHOLERA   IN    THE   FIELD        165 

done  to  add  fuel  to  the  flames,  and  in  being  al- 
lowed three  weeks'  respite  in  which  to  observe  the 
progress  of  an  outbreak. 

Irrespective  of  the  plan  we  choose,  if  new  cases 
continue  to  appear  later  than  the  sixth  or  seventh 
day  following  treatment,  a  second  dose  of  serum 
alone  is  indicated;  and  if  " breaks"  occur  subse- 
quent to  simultaneous  treatment,  they  should  be 
handled  in  the  manner  described  in  the  preceding 
chapter. 

Under  the  conditions  in  which  we  found  this 
herd  of  shoats,  we  explain  the  situation  to  the 
breeder,  and  recommend  method  number  three  as 
safest,  informing  him  at  the  same  time  that 
method  number  two  is,  in  the  majority  of  cases, 
satisfactory.  With  the  facts  before  him  he  can 
then  decide  for  himself. 

Precautions  to  prevent  spread  of  hog  cholera  to 
neighboring  farms  include  preventing  sale  or  ex- 
change of  sick  or  well  animals  from  the  infected 
herd,  exclusion  from  the  infected  pasture  of  all 
persons,  vehicles,  or  animals  that  may  later  enter 
non-infected  hog  quarters,  and  prompt  disposal 
of  carcasses  so  that  they  will  not  attract  carrion- 
eating  animals  or  birds.  Burning  is  by  far  the 
best  method  of  destroying  carcasses,  but  burying 
in  quicklime,  or  rendering,  is  permissible.  In  a 
pasture  such  as  we  find  this  herd  of  shoats  dis- 


166  HOG   CHOLEBA 

infectants  are  of  little  service,  and  we  must  de- 
pend on  natural  influences  (drying  and  sunlight) 
to  destroy  virus  which  contaminates  the  soil. 

Many  states  have  specific  regulations  governing 
precautions  against  interherd  spread  of  hog  chol- 
era, and  when  these  are  available  and  practicable 
they  should  be  followed.  None  of  the  shoats 
should  be  removed  earlier  than  thirty  days  follow- 
ing disappearance  of  all  sickness  from  the  herd, 
and  previous  to  their  removal,  if  they  are  to  min- 
gle with  cholera  susceptible  hogs  they  should  first 
be  dipped  or  sprayed  with  3  per  cent  compound 
cresol  solution.  It  is  legal  in  some  states,  in  han- 
dling a  herd  of  this  kind,  to  remove  apparently 
well  animals  for  immediate  slaughter  under  in- 
spection, but  except  in  unusual  circumstances  the 
practice  has  little  to  recommend  it. 

If  we  go  back  to  our  original  problem  and  as- 
sume alterations  in  the  conditions  there  outlined, 
corresponding  changes  in  the  plan  of  handling  will 
suggest  themselves,  and  the  reasons  for  these 
changes  will  appear.  If  hogs  are  closely  confined 
and  the  herd  is  badly  infected,  serum  alone  is  indi- 
cated, because  natural  infection  will  take  place 
and  produce  permanent  immunity  in  all  that  sur- 
vive ;  if  they  are  found  under  conditions  that  sug- 
gest low  resistance,  if  they  are  of  exceptional 
value,  or  if  the  owner  is  skeptical,  nervous,  or 
overcritical,  plan  number  three  should  be  recom- 


HANDLING   HOG   CHOLEEA   IN   THE   FIELD        167 

mended,  special  care  being  taken  to  build  up  the 
resistance  of  the  animals  during  the  interval  be- 
tween serum  alone  and  serum-virus  administra- 
tion. 

If,  as  is  sometimes  the  case,  we  are  compelled  to 
make  a  provisional  diagnosis  of  "hog  cholera,  we 
should  give  serum  alone  and  observe  the  future 
development  of  the  disease.  Provided  it  proves  to 
be  hog  cholera,  or  if  it  disappears  entirely  so  that 
doubt  still  remains,  we  may  give  simultaneous 
treatment  three  or  four  weeks  later;  if  it  proves 
to  be  some  other  malady,  and  if  hog  cholera  is  not 
in  the  vicinity,  simultaneous  treatment  should  not 
follow  unless  the  owner  wishes  to  maintain  an  im- 
mune herd.  Usually,  when  there  is  hog  cholera 
together  with  some  active  complication,  the  im- 
munity of  the  herd  should  be  maintained  on  serum 
alone  until  the  animals  are  in  fit  condition  to  re- 
ceive serum-virus  treatment.  This  may  require 
two  or  more  doses  of  serum  at  three  or  four  week 
intervals,  but  if  the  complication  is  of  such  nature 
that  it  cannot  be  controlled  after  serum  alone  is 
administered,  we  will  only  aggravate  it  if  we  give 
simultaneous  treatment. 

Methods  of  preventing  spread  of  hog  cholera  to 
neighboring  herds  are  also  somewhat  different 
when  we  find  the  infected  animals  closely  confined. 
We  gain  very  little  by  cleaning  and  disinfecting 
quarters  occupied  by  hogs  sick  with  cholera,  be- 


168  HOG    CHOLERA 

cause  each  time  an  infected  animal  urinates,  rein- 
fection of  its  pen  takes  place.  As  long  as  hog 
cholera  is  active  in  a  herd  we  should  devote  our 
attention  to  effective  quarantine,  prompt  disposal 
of  carcasses,  and  the  maintenance  of  ordinary 
cleanliness  that  is  at  all  times  conducive  to  the 
health  of  the  animals.  When  the  disease  disap- 
pears, all  contaminated  litter  should  be  burned, 
and  the  indoor  quarters  sprayed  with  3  per  cent 
lysol  or  compound  cresol  solution.  Often  appli- 
cation of  disinfectant  at  intervals  of  several  days 
is  advantageous.  Hog  cholera  virus  cannot  al- 
ways be  killed  in  outside  yards.  Spreading  a 
thick  layer  of  straw  over  the  yard  and  burning  it 
is  probably  most  effective,  but  this  is  not  always 
practicable.  Plowing  and  free  use  of  disinfec- 
tants hasten  destruction  of  the  virus,  but  the  lat- 
ter measure  is  useful  only  in  small  enclosures. 

Too  often  directions  given  for  disinfecting  quar- 
ters require  more  than  is  possible,  and  they  are  not 
specific.  If  we  are  careful  not  to  require  unneces- 
sary and  laborious  measures  we  will  secure  much 
better  cooperation  in  carrying  out  those  that  actu- 
ally are  essential;  and  if  surroundings  are  such 
that  we  find  it  impossible  to  give  detailed  and  spe- 
cific directions  for  cleaning  and  disinfecting,  we 
may  be  sure  that  the  general  admonition  to  "  clean 
and  disinfect "  will  do  very  little  good.  We  must 
recognize  the  fact  that  some  hog  quarters  cannot 


HANDLING   HOG    CHOLERA   IN    THE   FIELD         169 

at  once  be  freed  of  hog  cholera  virus,  at  least  by 
methods  within  reach  of  the  man  of  average 
means.  Under  such  circumstances,  if  hog  raising 
is  to  be  continued,  the  herd  should  be  maintained 
immune  to  hog  cholera. 

We  have  already  said  that  handling  a  herd  of 
infected  shoats  is  the  veterinarian's  simplest  duty 
in  dealing  with  hog  cholera.  We  will  now  con- 
sider some  of  the  more  complex  problems  that  field 
work  constantly  place  before  us.  Let  us  suppose 
that  in  addition  to  the  herd  of  infected  shoats 
there  is  on  the  same  farm,  some  distance  away,  a 
number  of  feeding  hogs  that  have  shown  no  signs 
of  disease.  If  the  animals  are  to  be  marketed 
in  less  than  four  weeks  they  may  receive  serum 
alone,  and  if  hog  cholera  does  not  appear  among 
them  in  the  course  of  six  or  seven  days,  it  is  allow- 
able to  kill  them  under  inspection;  if  marketing 
must  be  delayed  more  than  four  weeks,  simultane- 
ous treatment  is  indicated.  As  far  as  the  effect 
of  treatment  itself  is  concerned,  hogs  may,  if 
emergency  demands  it,  be  killed  for  food  as  early 
as  one  day  following  administration  of  serum 
alone,  but  if  serum  and  virus  are  given,  a  delay  of 
at  least  three  weeks  is  desirable. 

In  addition  to  feeders  we  encounter  on  practic- 
ally every  farm  a  considerable  number  of  breeding 
stock.  A  boar,  pregnant  sows,  some  just  farrow- 
ing, and  others  nursing  litters  make  up  the  repre- 


170  HOG   CHOLEKA 

sentative  farm  herd.  A  permanent  immunity  is 
desired  for  all  of  these,  and  we  follow  the  general 
plan  of  giving  simultaneous  treatment  to  all  ani- 
mals in  condition  to  receive  it,  and  protecting  the 
others  with  serum  alone  pending  the  time  when 
they  may  safely  receive  serum  and  virus. 

Assuming  that  breeding  stock  of  this  character 
is  on  the  farm  with  the  infected  shoats,  but  that 
after  numerous  temperatures  have  been  taken 
there  is  no  evidence  of  disease,  it  may  be  handled 
as  follows :  the  boar  may  be  given  serum  and  virus 
at  once,  or  if  he  is  of  exceptional  value,  follow-up 
treatment;  sows  in  early  pregnancy  may  be  han- 
dled in  the  same  manner,  but  always  after  the 
breeder  has  been  informed  that  simultaneous 
treatment  will  sometimes  produce  abortion,  and 
that  the  slight  danger  must  be  accepted  as  a  lesser 
evil ;  sows  due  to  farrow  in  less  than  three  weeks 
and  those  that  have  pigs  a  few  hours  or  days  old 
cannot  safely  receive  virus.  It  is  true  that  the 
infection  on  the  farm  will  in  most  cases  ultimately 
reach  them,  but  our  aim  should  be  to  delay  this  as 
long  as  possible,  and  to  protect  the  sows  with 
serum  alone  in  the  meantime.  Continued  isola- 
tion of  the  sows  is  desirable.  Two  or  even  three 
doses  of  serum  alone  at  three  or  four-week  inter- 
vals may  be  required  before  the  time  is  ripe  for 
the  final  simultaneous  treatment,  but  the  extra  ex- 
pense is  greatly  to  be  preferred  to  the  alternative 


HANDLING   HOG   CHOLEEA   IN    THE   FIELD         171 

— that  of  using  simultaneous  treatment  so  that  the 
sow  will  be  farrowing  or  nursing  a  newborn  lit- 
ter at  a  time  when  the  resulting  reaction  is  in 
progress. 

The  pigs  likewise  should  be  maintained  on  doses 
of  serum  alone  at  four-week  intervals  until  they 
are  at  least  nine  weeks  old,  preferably  twelve,  and 
then  they  should  receive  simultaneous  treatment. 
If  they  are  fairly  well  isolated  from  the  infected 
animals  the  first  dose  of  serum  alone  may  be  de- 
layed until  they  are  two  or  three  weeks  of  age, 
otherwise  it  should  be  given  when  they  are  only 
a  few  days  old.1 

aThe  question  whether  young  pigs  acquire  a  permanent  immu- 
nity as  a  result  of  simultaneous  treatment  is  yet  unanswered. 
Niles  describes  experiments  indicating  that  they  do,  while  Cahill 
on  the  other  hand  found  that  over  50  per  cent  of  several  hundred 
pigs  given  serum  and  virus  between  the  ages  of  two  and  eight 
weeks  failed  to  acquire  a  permanent  immunity  as  a  result.  Peter- 
sen  found  that  only  fifteen  out  of  one  thousand  ' '  baby  pigs ' ' 
given  simultaneous  treatment  proved  susceptible  as  old  hogs.  We 
have  collected  very  little  experimental  data  on  this  point,  the 
results  agreeing  substantially  with  those  of  Niles. 

Our  field  observations,  however,  lead  us  to  believe  that  a  per- 
manent immunity  is  not  always  established  when  serum  and  virus 
are  given  to  sucking  pigs.  In  one  instance  we  gave  simultaneous 
treatment  to  fifty  pigs  that  were  about  eight  weeks  old.  When 
the  animals  had  reached  a  weight  of  about  150  pounds,  one  of 
them  was  brought  to  us  for  autopsy  and  showed  undoubted  lesions 
of  hog  cholera.  Three  or  four  of  the  others  developed  symptoms 
of  the  disease  during  the  following  week,  so  the  entire  herd  was 
revaccinated.  Two  of  those  that  sickened  died  later  but  we  did 
not  have  an  opportunity  to  perform  autopsies.  There  is  little 
doubt  that  they  died  of  hog  cholera,  but  just  how  many  more 
would  have  died  in  the  absence  of  a  second  injection  is  a  matter 
of  conjecture.  In  another  instance  that  came  under  our  observa- 
tion about  eighty  young  pigs  were  given  simultaneous  treatment, 
and  when  these  animals  reached  a  weight  of  about  180  pounds 
each,  approximately  twenty  of  them  died.  We  performed  autop- 
sies on  several,  and  found  unmistakable  hog  cholera  lesions. 


172  HOG    CHOLERA 

We  have  been  called  on  repeatedly  to  handle 
herds  of  sows  infected  with  hog  cholera  just  at 
farrowing  time.  Whenever  it  is  possible  we  dip 
the  animals,  segregate  them  as  best  we  can  and 
administer  serum  alone,  carrying  both  sows  and 
pigs  along  with  doses  of  serum  alone  at  four- 
week  intervals  until  the  latter  are  weaned  and  at 
least  nine  weeks  old,  at  which  time  sows  and  pigs 
receive  simultaneous  treatment.  In  herds  in 
which  isolation  is  impossible,  we  follow  the  same 
course  in  regard  to  administering  serum,  giving 
the  first  dose,  about  4  mils,  when  the  pigs  are  a 
day  or  two  old.  It  is  possible  to  bring  pigs  safely 

These  observations  do  not  carry  the  weight  that  may  be  attached 
to  carefully  controlled  experiments,  but  they  suggest  caution  in 
regard  to  the  sweeping  conclusion  that  all  young  pigs  acquire 
permanent  immunity  as  a  result  of  simultaneous  treatment. 

Closely  bound  up  with  this  question  is  the  one  of  the  immunity 
of  sucking  pigs  to  hog  cholera.  Pickens  found  that  100  per  cent 
of  pigs  nursed  by  immune  mothers  were  themselves  immune,  but 
any  person  with  extensive  experience  in  handling  hog  cholera 
knows  that  we  cannot  always,  or  usually,  depend  on  this  immunity. 
We  have  repeatedly  seen  pigs  born  of  immune  mothers  and 
nursed  by  them  dead  with  hog  cholera  before  they  were  four 
weeks  old,  but  there  are  others,  as  Pickens'  experiments  show, 
that  are  immune. 

Collectively,  all  experimental  work  and  clinical  observations  so 
far  recorded  point  to  the  conclusion  that  some  pigs  of  cholera 
immune  mothers  are  themselves  immune,  and  others  are  not;  some 
will  acquire  active  immunity  as  a  result  of  simultaneous  treat- 
ment, others  will  not.  We  have  no  way  of  knowing  whether  any 
particular  young  pig  or  litter  will  acquire  permanent  immunity 
if  simultaneous  treatment  is  given,  so  we  prefer  to  maintain  the 
immunity  of  all  young  pigs  with  serum  alone,  and  to  finish  with 
simultaneous  treatment  when  the  animals  are  about  twelve  weeks 
old.  A  cheaper  plan  than  this  will  be  available  in  well-kept  herds 
f  the  findings  of  Niles  are  confirmed;  a  more  effective  one  is  not 
likely  to  be  found  as  long  as  we  use  serum  and  virus  as  they  are 
now  prepared.. 


HANDLING   HOG   CHOLEKA  IN    THE   FIELD         173 

through  an  outbreak  even  when  they  are  born  in 
pens  containing  hogs  sick  with  cholera,  and  this 
presents  no  great  difficulties  when  the  sows  are 
immune,  but  when  farrowing  and  recently  far- 
rowed sows  are  susceptible,  they  do  not  tolerate 
virus  well.  Despite  the  fact  that  they  receive 
serum  a  few  will  die,  other  will  fail  to  nurse  their 
litters,  and  on  the  whole  results  are  much  less 
satisfactory  than  they  are  when  reasonably  effec- 
tive isolation  can  be  practiced. 

We  do  not  wish  to  convey  the  impression  that 
after  hog  cholera  reaches  a  herd  we  can  prevent, 
by  isolation,  ultimate  infection  of  all  the  animals 
in  it  for  exactly  the  reverse  is  true.  The  point 
we  emphasize  is  that  when  the  disease  appears 
among  sows  that  are  farrowing,  infection  of  many 
of  them  can  be  delayed  by  isolation,  that  they  gain 
valuable  time,  and  they  and  their  litters  are  in 
better  condition  to  withstand  the  effects  of  the 
virus  when  later  it  reaches  them,  either  by  natural 
means  or  through  simultaneous  treatment.  A 
sow  undergoing  serum-virus  reaction  when  her 
litter  is  a  day  or  two  old  is  in  some  danger  of 
death,  and  even  if  she  lives  lactation  may  cease 
and  her  pigs  perish.  Delay  the  event  of  infection 
four  weeks,  and  regardless  of  how  it  affects  the 
sow  the  litter  can  be  saved.  The  theoretical 
grounds  for  handling  farrowing  sows  in  this  man- 
ner are  obvious,  but  we  recommend  the  plaij  of 


174  HOG   CHOLEEA 

isolation  only  because  repeated  trials  have  proved 
it  effective. 

Establishing  and  maintaining  a  hog  cholera 
immune  herd.  So  far  we  have  dealt  with  hog 
cholera  after  it  has  reached  the  herd.  We  are 
now  to  consider  methods  of  preventing  it  from  in- 
fecting the  herd,  which  yield  even  better  results. 
In  their  relation  to  the  prevention  of  hog  cholera, 
most  herds  fall  into  three  general  classes:  those 
from  which  the  virus  can  be  excluded ;  those  con- 
stantly threatened  with  hog  cholera;  and  pure- 
bred herds  from  which  immune  breeding  stock  is 
sold.  The  herds  in  the  first  class  do  not  require 
immunization;  those  in  the  other  two  classes  are 
best  maintained  immune. 

The  first  question  to  be  decided  when  a  client 
consults  his  veterinarian  is  whether  it  is  really 
necessary  for  the  herd  to  be  maintained  immune. 
Is  hog  cholera  prevalent  in  the  vicinity?  Has  it 
appeared  periodically  on  the  farm  in  question? 
Is  the  herd  subsisting  partially  or  wholly  on  gar- 
bage f  Is  the  breeder  buying  in  hogs  at  frequent 
intervals?  Does  he  take  sows  to  neighboring 
farms  to  be  bred,  or  are  sows  brought  to  his  farm 
for  the  same  purpose?  Has  he  an  established 
market  for  immune  breeding  stock,  or  does  he 
wish  to  establish  one?  Has  the  herd  access  to  a 
stream  that  may  be  contaminated  with  hog  chol- 
era virus  ?  If  all  these  questions  can  be  answered 


HANDLING   HOG   CHOLERA   IN   THE   FIELD         175 

in  the  negative  we  should  advise  the  breeder  not  to 
immunize.  It  is  an  unnecessary  expense,  and 
when  once  simultaneous  treatment  is  employed 
in  a  herd  there  is  some  danger  in  discontinuing 
its  use.  Pigs  thus  immunized  may  eliminate  vir- 
us, and  this  may  be  on  hand  to  infect  susceptible 
animals  that  subsequently  are  added  to  the  herd 
by  birth  or  purchase.  In  case  it  is  desired  to  dis- 
continue immunization,  at  least  four  months,  and 
preferably  six,  should  elapse  between  the  date 
when  simultaneous  treatment  is  last  used  on  the 
place,  and  that  of  the  introduction  of  susceptible 
recruits  into  the  herd.  All  of  these  facts  should 
be  perfectly  clear  to  the  breeder  before  virus  is 
used  in  his  herd. 

When  chances  of  infection  with  hog  cholera  are 
remote,  and  the  breeder  is  advised  against  main- 
taining an  immune  herd,  he  should  be  cautioned 
against  all  the  practices  that  may  result  in  the  in- 
fection of  his  swine.  He  should  also  be  informed 
regarding  the  things  that  would  lead  him  to  sus- 
pect the  presence  of  hog  cholera,  and  the  neces- 
sity for  early  reporting  of  an  outbreak,  should  it 
occur,  must  be  made  plain. 

When  hog  cholera  threatens  ultimately  to  attack 
a  herd  and  destroy  it  we  can  render  the  breeder 
no  greater  service  than  in  advising  him  to  main- 
tain it  immune  to  cholera.  Much  as  we  dislike  the 
idea,  in  the  abstract,  of  introducing  virus  into 


176  HOG    CHOLEEA 

new  territory,  our  experience  in  concrete  cases  is 
that  one  untreated  cholera  infected  herd  in  a 
neighborhood  is  more  of  a  menace  to  adjacent 
herds  than  ten  properly  maintained  immune  with 
simultaneous  treatment.  In  the  untreated,  in- 
fected herd,  there  is  a  great  temptation  sometimes 
to  sell  animals  before  a  diagnosis  of  cholera  is 
made,  some  breeders  are  slow  to  accept  the  fact 
that  hog  cholera  is  in  their  herds,  and  on  the 
whole  the  attack  comes  on  unheralded,  and  much 
damage  is  done  before  its  true  nature  is  realized. 
On  the  other  hand,  when  we  administer  simultane- 
ous treatment  to  a  herd  we  deliberately  establish 
our  defenses  against  the  spread  of  hog  cholera 
that  may  possibly  result  from  it,  the  period  of 
acute  danger  is  quickly  passed,  and  the  herd  is  no 
longer  a  menace  to  others  in  the  vicinity. 

When  once  the  breeder  decides  to  maintain  his 
herd  immune  to  cholera,  the  practice  must  be  faith- 
fully carried  out.  Between  keeping  all  animals 
immune  to  cholera  at  all  times  and  declining  to 
use  any  virus  whatever,  there  is  no  middle  ground. 
We  cannot  temporize  with  a  disease  like  hog  chol- 
era. Like  the  proverbial  nettle,  simultaneous 
treatment  incident  to  maintaining  a  cholera-im- 
mune herd  must  be  grasped  firmly  or  avoided  alto- 
gether, for  it  will  not  do  to  have  virus  and  suscep- 
tible pigs  in  the  herd  at  alternate  intervals. 
Sooner  or  later  the  two  will  get  together. 


HANDLING    HOG    CHOLERA   IN    THE    FIELD         177 

Let  us  suppose  that  a  breeder  of  pure-bred  hogs 
wishes  to  establish  a  trade  for  immune  breeding 
animals,  and  has  decided  to  maintain  a  cholera  im- 
mune herd.  His  herd  consists  of  two  large  herd 
boars,  fifty  brood  sows  nursing  litters  about  four 
weeks  old,  fifty  gilts  recently  bred  and  now  being 
sold  daily  in  twos  and  threes  as  the  trade  de- 
mands, and  a  herd  of  one  hundred  fattening  hogs 
that  will  be  ready  for  market  in  six  weeks.  Hog 
cholera  is  not  threatening  the  herd.  How  is"  it 
to  be  handled  with  the  greatest  safety,  and  with 
the  least  expense  and  inconvenience? 

The  brood  sows  are  not  in  the  best  condition  to 
receive  simultaneous  treatment,  the  gilts  could  not 
be  sold  and  shipped  at  once  if  it  were  given,  and 
the  fattening  hogs  will  be  sold  anyhow  in  six 
weeks.  If  we  wait  that  length  of  time  the  gilts 
also  will  be  sold,  the  young  litters  will  be  weaned, 
and  sows  and  pigs  will  be  in  condition  to  receive 
simultaneous  treatment.  The  two  boars  are  thus 
the  only  animals  in  the  herd  for  which  the  delay 
of  six  weeks  is  not  positively  indicated,  and  they 
can  be  immunized  as  well  at  one  time  as  another. 

From  this  concrete  example  we  develop  the  sim- 
ple rule  that  when  choice  is  allowed  we  begin  im- 
munizing at  a  time  when  the  herd  is  at  a  minimum 
as  far  as  numbers  of  adult  breeding  stock  is  con- 
cerned, and  when  the  animals  are  in  condition  to 
receive  simultaneous  treatment  with  the  least  pos- 


178  HOG   CHOLEEA 

sible  risk.  In  the  average  farm  herd  the  most 
opportune  time  to  immunize  is  three  or  four  weeks 
after  the  spring  litters  are  weaned. 

On  the  other  hand,  when  the  herd  is  immediately 
threatened  with  hog  cholera  we  have  no  choice  but 
to  accept  it  as  it  is,  and  protect  it  at  once.  Under 
such  circumstances  the  plan  is  to  give  simultane- 
ous treatment  to  all  animals  in  condition  to  re- 
ceive it,  and  serum  alone  to  the  remainder.  Every 
four  weeks  we  return  and  repeat  the  process,  con- 
fining the  treatment  to  those  that  received  serum 
alone  previously,  until  the  entire  herd  has  received 
simultaneous  treatment,  and  permanent  immunity 
has  thus  been  established. 

When  once  the  adult  breeding  stock  is  immune, 
our  task  is  then  to  immunize  the  young  litters  as 
they  come  on.  This  is  relatively  simple  for  the 
veterinarian  and  inexpensive  for  the  breeder. 
On  farms  where  methods  of  swine  husbandry  are 
the  best,  and  at  times  when  there  appears  to  be 
little  immediate  danger  from  hog  cholera,  the  best 
plan  is  to  keep  close  watch  on  the  pigs  until  they 
are  about  twelve  weeks  old  and  then  give  simul- 
taneous treatment.  In  many  herds  though,  es- 
pecially the  large  garbage-fed  herds  in  the  East, 
a  high  percentage  of  the  pigs  will,  if  left  unpro- 
tected, contract  hog  cholera  before  they  reach  an 
age  approaching  twelve  weeks,  and  a  considerable 
number  that  do  not  actually  contract  the  disease 


HANDLING   HOG   CHOLERA   IN   THE   FIELD        179 

will  fail  to  develop  so  as  to  be  fit  subjects  for 
simultaneous  treatment.  In  these  herds,  the  only 
effective  plan  we  know  of  is  to  protect  the  pigs 
with  serum  alone  until  they  are  old  enough  and  in 
proper  condition  to  receive  serum  and  virus.  Un- 
der ordinary  conditions  the  pigs  receive  serum 
alone  when  they  are  between  three  and  six  weeks 
of  age,  they  are  weaned  when  they  are  about 
eight  weeks  old  and  receive  simultaneous  treat- 
ment two  to  four  weeks  later.  It  is  best  to  cas- 
trate them  as  sucklings.  Under  exceptional  con- 
ditions we  are  compelled  to  give  more  than  one 
dose  of  serum  alone  before  the  time  is  ripe  for 
simultaneous  treatment,  but  an  extra  dose  of  se- 
rum for  a  small  pig  is  not  expensive. 

We  have  used  this  general  plan  since  1912, 
starting  with  several  garbage-fed  and  cholera  in- 
fected herds  in  quarters  that  did  not  permit  clean- 
ing and  disinfecting,  and  protecting  all  subsequent 
litters  of  pigs,  year  after  year,  with  losses  from 
all  causes  totaling  considerably  less  than  five  per 
cent.  We  know  of  several  other  veterinarians  who 
have  obtained  like  results  during  a  term  of  years, 
and  we  do  not  know  of  a  single  instance  where  the 
plan  has  been  followed  consistently  and  found 
wanting.  The  preliminary  doses  of  serum  alone 
are  not  necessary  in  all  herds,  but  we  may  resort 
to  them  confidently  under  conditions  such  as  we 
have  described. 


180  HOG   CHOLEKA 

Several  points  that  contribute  to  the  success  of 
maintaining  an  immune  herd  remain  to  be  men- 
tioned. Especially  in  large  herds  it  is  a  good 
practice  to  mark  each  pig  at  the  time  it  is  immun- 
ized so  that  it  can  be  positively  identified.  Other- 
wise we  are  likely  to  miss  an  occasional  pig  or  lit- 
ter, and  if  these  untreated  animals  subsequently 
contract  hog  cholera,  we  are  called  to  account  for 
deaths  for  which  we  are  in  no  way  responsible. 
We  should  also  suggest  to  the  breeder  the  advan- 
tage of  breeding  several  sows  near  the  same  time, 
so  that  a  considerable  number  of  pigs  can  be  im- 
munized at  one  time.  In  addition  to  economy  in 
immunizing  this  practice  enables  the  breeder  to 
provide  foster  mothers  for  pigs  farrowed  by  sows 
which  on  account  of  death  or  disease  incident  to 
parturition  are  unable  to  nurse  their  litters. 

It  is  important  that  pigs  shall  grow  steadily  and 
rapidly  from  birth  until  the  time  when  simultane- 
ous treatment  is  administered.  Influences  that  re- 
tard growth  usually  lower  resistance  as  well  and 
we  are  thus  compelled  to  maintain  the  immunity 
of  poorly  nourished  pigs  with  serum  alone  much 
longer  than  is  necessary  in  handling  thrifty  pigs. 
Any  suggestions  that  will  aid  the  breeder  to  grow 
pigs  rapidly  during  the  first  three  months  of  their 
lives  will  be  greatly  to  his  advantage. 

Handling  feeding  hogs.  A  common  practice 
on  farms  in  many  parts  of  the  country,  more  par- 


HANDLING   HOG   CHOLERA   IN    THE    FIELD         181 

ticularly  in  the  corn-belt,  is  that  of  purchasing 
feeding  shoats  in  the  fall  of  the  year  to  consume 
the  season 's  crop  of  grain.  The  general  tendency 
is  for  these  shoats  to  be  raised  in  regions  where 
land  is  rather  cheap,  and  fattened  in  localities 
where  higher-priced  land  compels  a  more  inten- 
sive type  of  farming.  Direct  communication  be- 
tween the  breeders  who  raise  the  shoats  and  the 
feeders  who  finish  them  is  not  generally  main- 
tained. The  breeder  seeks  a  seller's  market  in 
cities  where  there  are  large  stockyards,  and  the 
feeder  habitually  goes  to  these  places  to  buy.  Be- 
fore the  discovery  of  anti-hog-cholera  serum,  long 
years  of  bitter  experience  had  taught  feeders  that 
hogs  which  pass  through  large  public  stockyards 
very  often  contract  cholera.  As  soon  as  the  serum 
was  discovered  it  was  eagerly  seized  on  in  at- 
tempts to  protect  stockyard  shoats  that  subse- 
quently were  to  be  shipped  to  other  farms  to  be 
fattened.  The  desire  was  to  give  these  animals 
permanent  immunity  to  hog  cholera,  so  it  grew  to 
be  a  general  practice  to  administer  simultaneous 
treatment  to  them  in  the  yards,  and  ship  them  in 
the  course  of  a  few  days  to  the  feeder's  farm. 
Years  of  experience  prove  that  this  practice, 
though  perhaps  an  improvement  over  old  meth- 
ods, is  frequently  the  cause  of  heavy  losses,  both 
in  the  immediate  animals  treated  and  in  hogs 


182  HOG   CHOLERA 

with  which  they  come  in  contact  after  they  reach 
their  various  destinations. 

Those  who  follow  the  practice  are  merely  lucky 
if  they  do  not  sustain  heavy  losses  because  they 
continually  ignore  the  fact  that  a  reaction  nor- 
mally follows  simultaneous  treatment,  and  that 
shipping  lowers  the  resistance  of  hogs  to  such 
an  extent  that  the  reaction  may  prove  fatal. 
When  we  add  to  the  effects  of  shipping  and  simul- 
taneous treatment  those  incident  to  a  brief  or 
prolonged  .stay  in  infected  yards  before  the  treat- 
ment is  administered,  as  well  as  those  that  grow 
out  of  injudicious  feeding  and  watering  when  the 
animals  reach  the  end  of  a  journey,  fatigued,  hun- 
gry, and  thirsty,  we  have  a  chain  of  devitalizing 
influences  that  often  cause  disaster. 

It  is  well  known  also  that  many  swine  unloaded 
at  stockyards  do  not  leave  home  free  from  dis- 
ease. Oftentimes  a  consignment  of  hogs  repre- 
sents a  breeder's  final  determination  to  "cash  in" 
on  a  herd  that  is  badly  infested  with  parasites, 
that  is  suffering  with  some  obscure  respiratory 
disease,  or  one  that  has  recently  contracted  hog 
cholera.  Despite  the  fact  that  apparently  well 
animals  are  selected  from  such  herds  for  shipping 
each  animal  selected  is  potentially  the  source  of 
future  trouble.  What  is  one  to  expect  if  in  pur- 
chasing hogs  for  the  feed-yard  he  chances  to  in- 
clude even  a  few  individuals  of  this  kind?  The 


HANDLING   HOG   CHOLEEA   IN    THE   FIELD        183 

mere  fact  that  many  lots  of  shoats  are  shipped 
long  distances  to  stockyards  and  after  receiving 
simultaneous  treatment  are  at  once  reconsigned 
to  distant  localities  which  they  reach  without  im- 
mediate or  subsequent  mishap  has  little  bearing 
on  the  problem  as  a  whole.  It  is  the  fact  that 
many  lots  of  hogs  will  not  endure  such  handling, 
and  that  we  cannot  always  distinguish  in  advance 
between  those  that  will  and  those  that  will  not, 
that  still  troubles  us.  This  aspect  of  the  subject 
will  receive  further  attention  in  the  chapter  on 
"The  Control  and  Eradication  of  Hog  Cholera. " 

Let  us  assume  that  a  man  living  in  western  New 
York  requires  two  hundred  shoats  as  feeders. 
His  natural  purchaser's  market  is  in  the  stock- 
yards at  Buffalo,  or  further  west  in  the  hog-rais- 
ing districts  of  Ohio.  He  knows  that  there  are 
certain  dangers  connected  with  shipping  hogs  and 
he  consults  his  veterinarian  in  order  to  learn  how 
they  can  be  avoided.  What  precautions  should 
he  be  advised  to  take? 

Other  things  being  equal  it  is  best  to  purchase 
direct  from  the  farm,  for  this  avoids  unloading 
animals  at  large  stockyards,  and  it  is  much  easier 
to  determine  the  true  condition  of  hogs  when  we 
examine  them  in  what  may  be  termed  their  nor- 
mal habitat  than  when  we  inspect  them  hurriedly 
during  the  excitement  and  confusion  that  prevails 
at  the  average  stockyard.  If  immune  feeders  can 


184  HOG    CHOLERA 

be  purchased  from  a  reliable  source  on  the  farm, 
that  is  by  far  the  most  satisfactory  plan.  In 
case  that  is  impossible,  our  client  should  be  ad- 
vised to  purchase  from  thrifty  farm  herds  and  to 
assemble  the  animals  on  a  stated  day  at  a  local 
shipping  point.  They  should  then  be  given  serum 
alone,  placed  in  clean  comfortable  well-bedded 
cars,  and  shipped  at  once  to  their  destination. 
When  they  arrive  at  the  feeder 's  farm,  they  should 
be  placed  in  dry  comfortable  quarters  and  fed 
sparingly  on  light  foods  for  a  few  days.  After 
they  become  accustomed  to  the  change  in  feed  and 
quarters — say  in  two  or  three  weeks — they  should 
be  given  simultaneous  treatment. 

If  circumstances  compel  our  client  to  purchase 
at  the  stockyards,  he  should  if  possible  see  the 
animals  unloaded,  and  in  any  event  he  should  not 
select  animals  that  have  been  in  the  yards  several 
days.  It  is  best  to  avoid  mixed  lots  of  hogs,  and 
those  that  contain  a  considerable  number  of  dead 
animals  when  they  arrive  at  the  yards,  for  these 
often  are  shipped  to  market  because  of  disease. 
Hogs  that  cough  persistently  should  not  be  ac- 
cepted. When  once  the  selection  is  made  the  ani- 
mals should  be  given  serum  alone  without  delay 
and  shipped  at  once  to  their  destination.  When 
they  arrive  at  the  feeder's  yards  they  require  han- 
dling similar  to  that  accorded  animals  purchased 
directly  from  the  farm. 


HANDLING   HOG   CHOLERA   IN   THE   FIELD         185 

Careful  and  experienced  men  can  usually  select 
satisfactory  feeders  in  large  stockyards,  but  on 
the  whole  there  are  unavoidable  risks  associated 
with  the  practice. 

Handling  show  hogs.  Show  hogs  constitute 
a  separate  problem  in  themselves,  because  they 
are  of  exceptional  value,  and  because  they  must 
necessarily  be  subjected  to  handling  entirely  dif- 
ferent from  that  accorded  the  ordinary  farm  or 
market  hog.  It  is  not  uncommon  for  show  hogs 
to  contract  cholera  during  contact  with  other 
swine  in  the  show  ring  or  in  transit  from  fair  to 
fair,  and  not  infrequently  they  arrive  home  appar- 
ently well,  and  develop  symptoms  of  the  disease 
during  the  few  days  following,  thus  infecting  the 
entire  herd  which  they  represent.  This  experi- 
ence has  been  so  common  that  the  practice  of 
showing  hogs  that  are  not  immune  to  cholera  is 
indefensible.  Some  fair  associations  require  cer- 
tificates to  the  effect  that  hogs  are  immune  to  chol- 
era before  they  will  admit  them  to  the  show  ring. 

The  breeder  who  maintains  his  herd  immune  to 
cholera  has  no  difficulties  to  face  from  this  quar- 
ter, for  as  far  as  hog  cholera  is  concerned,  he  may 
send  his  animals  out  on  the  fair  circuit  secure  in 
the  knowledge  that  they  will  not  themselves  be- 
come infected,  nor  be  instrumental  in  infecting 
others  with  which  they  come  in  contact. 

The  breeder  whose  herd  is  susceptible  to  cholera 


186  HOG    CHOLEKA 

must  have  his  show  hogs  simultaneously  treated 
at  least  thirty  days  before  they  leave  for  the  fairs, 
or  else  he  must  give  them  serum  alone  at  the 
time  they  start,  and  repeat  the  treatment  at  three- 
week  intervals  as  long  as  they  are  on  the  road. 
Neither  plan  is  entirely  free  from  objection,  but 
either  is  far  from  better  than  to  neglect  immun- 
izing. If  simultaneous  treatment  is  given  this 
necessitate*,  the  introduction  of  virus  on  a  farm 
where  there  are  untreated  susceptible  hogs,  and 
thus  it  is  applicable  only  where  there  are  facili- 
ties for  effective  segregation  of  the  show  hogs. 
If  serum  alone  is  given  and  the  hogs  are  infected 
with  cholera  at  the  fairs  they  must  pass  through 
the  resulting  reaction  at  a  time  when  they  are  low 
in  resistance,  and  if  the  reaction  is  so  severe  that 
it  results  in  virus  excretion,  there  is  danger  that 
in  returning  from  the  fair  circuit  the  show  hogs 
may  infect  the  home  herd. 

If  simultaneous  treatment  is  to  be  given  show 
animals  and  the  remainder  of  the  herd  is  to  re- 
main susceptible  to  cholera,  the  following  plan 
is  safest:  isolate  the  show  hogs  in  quarters  that 
will  permit  subsequent  disinfection  and  give  them 
serum  and  virus;  if  during  the  next  thirty  days 
none  of  the  animals  develop  visible  sickness,  dip 
or  spray  them  thoroughly,  using  3  per  cent  com- 
pound cresol  solution,  and  send  them  out  on  the 
show  circuit;  when  they  return,  it  is  best  to  dip 


HANDLING    HOG    CHOLEKA   IN    THE    FIELD         187 

them  a  second  time  before  they  are  placed  with 
susceptible  hogs,  and  where  there  are  facilities 
for  isolating  them  two  weeks  after  they  return 
this  should  be  done  as  an  additional  precaution. 
We  must  not  lose  sight  of  the  fact  that  even  an 
immune  hog  can  become  the  intermediate  carrier 
of  hog  cholera  virus. 

Should  a  ' '  break "  appear  when  the  show  hogs 
are  immunized  it  should  be  handled  according 
to  the  plan  previously  outlined,  and  as  an  addi- 
tional precaution,  the  entire  herd  had  best  be  pro- 
tected with  serum.  In  any  event,  when  the  hogs 
leave  the  quarters  in  which  they  are  placed  for 
simultaneous  treatment,  the  pens  should  be  care- 
fully disinfected. 

When  no  virus  is  to  be  used  in  treating  the  show 
animals  they  require  serum  alone  at  the  time 
they  leave  home,  and  thereafter  every  three  weeks 
as  long  as  they  are  on  the  road.  After  they  re- 
turn it  is  well  to  isolate  them  two  weeks,  after 
which  they  may  be  dipped  in  antiseptic  solution 
and  placed  with  the  remainder  of  the  herd. 

On  the  whole,  a  breeder  who  habitually  places 
hogs  in  the  show  ring  should  maintain  his  entire 
herd  immune  to  hog  cholera.  Under  most  cir- 
cumstances, when  this  is  not  done  the  use  of  serum 
alone  for  temporary  protection  is  indicated,  but 
under  exceptional  conditions,  where  perfect  seg- 
regation is  possible  simultaneous  treatment  may 


188  HOG   CHOLERA 

be  given  the  show  animals.  Not  infrequently  the 
practitioner  has  the  question  of  immunization 
thrust  on  him  as  an  eleventh-hour  consideration 
just  on  the  eve  of  the  departure  of  show  hogs  for 
the  fairs.  In  this  event  he  has  no  legitimate 
choice  but  to  protect  the  animals  with  serum 
alone  during  the  period  of  probable  exposure. 

ORDERING  SERUM 

Every  veterinarian  in  country  practice  is  likely 
sooner  or  later  to  be  called  on  to  immunize  swine 
against  hog  cholera,  and  because  much  immuniz- 
ing consists  of  emergency  work,  serum  must  be 
procured  without  delay.  For  this  reason  the  vet- 
erinarian should  establish  relations  with  a  reput- 
able laboratory  near  at  hand  so  that  telegraphic 
orders  from  him  will  be  filled  promptly.  Because 
they  cannot  assume  responsibility  for  products 
that  have  been  in  other  hands,  most  laboratories 
will  not  allow  credit  for  returned  serum  and  virus 
and  thus  it  is  desirable  to  order  the  exact  quanti- 
ties required. 

Before  ordering  serum  the  veterinarian  should 
ascertain  the  number  of  hogs  to  be  vaccinated,  and 
their  approximate  weights.  A  representative  list 
would  appear  thus: 

1  boar,  weight  600  pounds 

8  sows,  weight  400  pounds  each 

65  pigs,  weight  20  pounds  each 

50  shoats,  weight  60  pounds  each 


HANDLING   HOG   CHOLERA   IN    THE   FIELD         189 

The  common  tendency  is  to  estimate  weights  of 
swine  far  too  low,  and  this  should  be  thought  of 
in  connection  with  every  serum  order. 

Before  the  list  is  completed  the  final  question, 
"Have  you  any  other  hogs?"  should  always  be 
asked,  for  it  is  very  annoying  and  very  common  to 
find,  even  after  we  reach  a  farm  to  do  the  immun- 
izing, that  the  owner  has  hogs  which  he  has  not 
mentioned  because  he  "hadn't  thought  of  having 
them  immunized. "  If  a  simultaneous  treatment 
is  to  be  given  to  any  of  the  hogs  in  a  herd,  the 
remainder  must  not  go  long  without  some  kind 
of  immunization,  and  lack  of  sufficient  serum  to 
treat  an  entire  herd  may  often  postpone  the  date 
of  treatment  or  necessitate  a  second  call. 

When  all  of  the  hogs  that  are  in  the  herd  are 
listed,  the  veterinarian  can  estimate  the  quantity 
of  serum  and  virus  required,  provided  he  has  a 
dose  table  from  the  laboratory  he  patronizes. 
Lacking  this,  he  should  send  in  the  list  and  allow 
the  laboratory  to  make  the  estimate. 

Telegrams  or  letters  containing  orders  such  as 
"Serum  and  virus  for  20  swine "  or  "Serum  to 
treat  a  mixed  bunch  of  100  sows,  pigs  and  shoats ' ' 
are  not  sufficient.  Every  order  should  state  the 
required  quantity  of  each  product,  or  it  should 
include  a  list  of  the  number  of  hogs  and  their 
approximate  weights. 


190  HOG   CHOLEEA 

Most  field  work  falls  within  the  scope  of  the  con- 
crete instances  outlined  in  this  chapter,  but  it  is 
necessary,  as  we  endeavored  to  make  clear  in  the 
beginning,  for  one  who  handles  hog  cholera  to 
understand  hog  cholera.  Our  aim  throughout  has 
been  to  show  why  as  well  as  what,  but  if  we  have 
fallen  short  of  this  aim  we  can  at  least  assure  our 
readers  that  the  methods  recommended  are  con- 
servative and  effective,  and  that  they  have  been 
developed  as  a  result  of  years  of  field  and  labora- 
tory experience. 

One  final  thought.  The  beginner  in  hog  cholera 
work  sooner  or  later  finds  himself  face  to  face 
with  some  baffling  situation.  A  herd  seems  in 
need  of  immediate  protection  but  doubt  in  regard 
to  diagnosis,  doubt  as  to  whether  the  complete 
history  of  the  herd  has  been  frankly  laid  before 
him,  and  the  question  whether  complete  coopera- 
tion will  be  accorded  him  in  the  subsequent  han- 
dling of  the  herd,  render  selection  of  the  method 
of  immunizing  difficult  to  make.  "When  in  doubt 
and  emergency  requires  immediate  protection  of  a 
herd,  use  serum  alone;  then  follow  with  simulta- 
neous treatment  in  less  than  four  weeks  if  subse- 
quent development  of  the  disease  requires  it"  is 
the  final  caution  we  leave  with  the  beginner. 


DANDLING   HOG   CHOLEKA   IN    THE   FIELD         191 

The  Veterinarian's  Charge  for  Serum  and  Its 
Administration 

If  a  veterinarian  expects  to  remain  long  in  prac- 
tice he  must  render  service  worth  much  more  than 
the  charge  he  attaches  to  it,  and  the  benefit  derived 
from  his  calls  must  be  obvious  to  his  clients.  The 
fact  that  immunization  of  hogs,  especially  large 
herds  in  localities  where  hog  cholera  is  prevalent, 
results  in  a  great  and  obvious  saving  to  the 
breeder  has  placed  this  phase  of  veterinary  prac- 
tice almost  in  a  class  by  itself.  We  do  not  ac- 
tually render  a  greater  service  in  checking  an  out- 
break of  hog  cholera  than  we  do  in  eradicating 
tuberculosis  from  a  cattle  breeder's  herd,  but  hog 
cholera  is  an  acute  and  fatal  disease  and  the 
direct  saving  due  to  its  control  is  far  more  appar- 
ent to  the  breeder  than  some  other  services, 
equally  as  valuable,  that  we  render  him.  Because 
of  this  fact,  and  because  of  the  great  demand  that 
has  existed  for  the  services  for  veterinarians  in 
immunizing  swine,  certain  abuses  in  regard  to 
charges  for  serum  administration  have  come  to 
light.  Complaints  have  been  leveled  at  a  few 
shortsighted  and  greedy  individuals,  but  they  have 
reacted  to  the  dicredit  of  the  profession  as  a 
whole.  Especially  when  large  numbers  of  hogs 
are  vaccinated  in  one  day,  when  charge  is  made  by 
the  head,  and  a  profit  greater  than  is  fair  is  added 


192  HOG    CHOLERA 

to  the  serum  used,  the  veterinarian  goes  home 
leaving  his  client  believing  that  he,  and  other 
members  of  the  profession,  are  shameless  prof- 
iteers. The  natural  inference  is  that  other  pro- 
fessional charges  as  well  are  exorbitant,  and  this, 
as  all  veterinary  practitioners  know,  is  not  true. 
When  immunization  of  a  herd  of  hogs  is  really 
indicated  and  when  a  veterinarian  does  the  work 
thoroughly  and  conscientiously,  he  renders  a  great 
and  obvious  service,  and  is  entitled  to  a  fee  con- 
siderably above  that  which  the  average  breeder  is 
inclined  to  regard  as  fair.  The  breeder  would  be 
surprised  if  he  knew  the  cost  of  waste,  breakage, 
and  overhead  which  the  veterinarian  must  pay. 
We  believe  though,  that  instead  of  courageously 
charging  fees  which  are  actually  their  due,  and 
which  will  enable  them  to  use  first-class  products 
and  do  careful  work,  too  many  veterinarians  have 
yielded  to  a  temptation  to  collect  their  fees,  un- 
known to  the  breeder,  in  the  form  of  profit  on  the 
serum  used.  The  purchase  price  of  the  serum 
sooner  or  later  comes  to  light  and  in  the  absence 
of  previous  explanation,  the  breeder  naturally  be- 
lieves that  the  difference  between  the  price  the 
veterinarian  pays  and  the  price  he  charges  his 
clients  for  serum  is  all  profit.  Real  and  imagin- 
ary abuses  in  this  direction  have  led  to  actual  and 
proposed  legislation  designed,  on  the  one  hand, 
to  place  vaccination  of  hogs  largely  in  the  hands 


DANDLING  HOG  CHOLEKA  IN  THE  FIELD       193 

of  laymen,  and  on  the  other  hand  to  fix  the  margin 
of  profit  which  the  veterinarian  may  charge,  or  at 
least  to  prevent1  him  from  concealing  from  his 
client  the  purchase  price  of  the  serum  he  uses. 

Legislation  of  the  former  type  can  result  only  in 
disaster  to  the  swine  industry  and  harm  to  the 
veterinary  profession,  but  we  do  not  believe  there 
are  good  reasons  why  the  purchase  price  of  serum 
should  not  be  known  to  the  breeder.  Obviously 
the  profession  puts  itself  in  a  bad  light  when  it 
opposes  legislation  of  this  kind,  unless  it  can  justly 
be  opposed  on  the  ground  that  the  handling  charge 
proposed  is  not  sufficient  to  cover  costs  of  waste 
and  breakage.  Such  opposition  only  gives  sub- 
stance to  the  suspicion  that  there  is  something 
to  conceal.  It  is  a  principle  which  should  be  ob- 
vious to  all  that  if  the  veterinary  profession  is  to 
retain  exclusive  rights  to  administer  serum  and 
virus  it  must  exercise  these  rights  in  a  manner  to 
justify  this  exclusion ;  and  any  legislative  attempts 
to  discipline  the  occasional  renegade  who  habitu- 
ally reaps  an  excessive  profit  on  serum  should, 
and  we  believe  will  be,  welcomed  by  the  better  ele- 
ment in  the  veterinary  profession. 

The  veterinarian's  fee  for  his  work  is  his  own 
private  concern,  and  the  compensation  he  can  com- 
mand depends  for  the  most  part  on  the  skill  and 
knowledge  which  he  employs  to  benefit  his  client ; 
but  the  best  interests  of  the  public  demand  that  the 


194  HOG    CHOLEKA 

use  of  serum  and  virus  shall  be  placed  exclusively 
in  his  hands,  and  when  this  is  done  he  has  not  the 
same  right  to  fix  the  selling  price  of  these  products 
that  he  has  to  name  his  own  fee.  Use  of  serum 
and  virus  is  a  public  trust  reposed  in  him  rather 
than  a  monopoly  given  into  his  hands  for  private 
exploitation.  His  profits  should  come  from  his 
work,  not  from  the  serum  he  uses. 

Some  practitioners  charge  according  to  the  num- 
ber of  hogs  treated,  some  according  to  the  quantity 
of  serum  injected,  and  others  on  the  basis  that 
they  fix  fees  for  other  calls.  vNo  system  is  entirely 
free  from  objection,  but  we  believe  that  the  most 
satisfactory  and  fair  plan  is  for  the  veterinarian 
to  place  a  value  on  his  day's  work  and  charge  for 
vaccinating  according  to  the  time  consumed  in 
doing  it.  He  is  entitled  to  add  to  this  a  handling 
charge  on  the  serum  he  uses,  to  compensate  for 
clerical  work,  express,  breakage,  and  unused  prod- 
ucts that  are  left  on  his  hands.  Under  ordinary 
conditions,  if  breeders  pay  cash,  an  increase  of  20 
or  25  per  cent  over  the  purchase  price  will  take 
care  of  these  items,  but  it  will  not  be  sufficient  if 
credit  is  habitually  allowed.  A  practitioner  can 
lose  more  on  one  bad  serum  bill  than  he  can  collect 
as  fees  for  several  days'  work. 

The  practice  of  charging  according  to  the  time 
consumed  has  obvious  advantages  if  we  let  our 
clients  know  that  we  are  following  it.  It  con- 


HANDLING   HOG   CHOLEftA   IN   THE   FIELD         195 

sumes  less  time  to  vaccinate  a  given  number  of 
hogs  for  a  client  who  will  have  the  animals  se- 
curely penned  in  clean  dry  quarters,  and  plenty  of 
help  ready  for  work  when  the  veterinarian  ar- 
rives, than  it  does  to  vaccinate  one-fourth  that 
number  for  a  man  who  awaits  the  veterinarian's 
arrival  and  then  begins  a  frantic  or  leisurely 
search  for  gates,  lumber,  ropes,  and  other  needed 
paraphernalia.  A  veterinarian  cannot  consume 
several  hours  in  vaccinating  a  small  lot  of  pigs 
and  at  the  same  time  keep  his  fee  at  a  figure  that 
the  breeder  can  afford  to  pay.  The  breeder  who 
provides  facilities  and  help  so  that  the  work  may 
be  done  dexterously  and  rapidly  should  profit  by 
his  foresight;  the  one  who  is  neglectful  must  ex- 
pect to  pay  for  his  negligence. 

Emergency  hog  cholera  practice,  that  is,  the 
care  of  herds  already  infected,  will  come  regularly 
to  a  man  who  handles  it  with  only  a  fair  degree 
of  effectiveness.  Under  such  circumstances  even 
average  veterinary  service  is  far  better  than  none. 
The  same  rule  does  not  apply  in  maintaining  im- 
mune herds,  the  phase  of  hog  cholera  control  that 
offers  greatest  satisfaction  to  both  practitioner 
and  breeder.  If  the  breeding  in  a  herd  is  so  or- 
dered that  a  large  number  of  pigs  can  be  vaccin- 
ated at  one  time,  if  the  animals  are  grown  rapidly 
and  conditioned  so  that  they  will  withstand  simul- 
taneous treatment  at  an  early  age,  and  if  the 


196  HOG   CHOLERA 

breeder  habitually  provides  facilities  that  allow 
vaccinating  to  be  done  without  loss  of  time,  the 
cost  per  head  can  be  kept  at  a  minimum.  The 
veterinarian  who  so  advises  his  clients  as  to  bring 
these  things  about  is  the  only  one  who  can  hope 
to  enlarge  m's  swine  practice  and  gain  lasting 
success  in  hog  cholera  work.  A  system  of  wireless 
which  we  do  not  completely  understand,  but  which 
nevertheless  spreads  intelligence  rapidly  and  un- 
erringly in  country  districts,  will,  in  each  veterin- 
arian's community  ultimately  convey  the  news 
that  immunizing  pays,  or  that  it  does  not  pay ;  and 
the  veterinarian  must  have  it  whispered  abroad 
that  immunizing  their  herds  pays  his  clients  or 
he  will  "kill  the  goose  that  lays  the  golden  egg." 


CHAPTER  X 

HOG    CHOLERA,    MEAT    INSPECTION    AND    GARBAGE 
FEEDING 

HOG  cholera  is  a  widespread  disease  affecting 
just  one  species  of  animal  used  solely  to  produce 
meat  for  human  food,  and  its  status  as  far  as  meat 
inspection  is  concerned  is  necessarily  well  estab- 
lished. The  following  paragraphs  from  Edel- 
mann1  set  forth  the  broader  principles  which  gov- 
ern the  formulation  of  more  detailed  and  specific 
regulations  which  are  in  force  in  various  abattoirs 
throughout  the  country : 

"Judgment  of  the  meat  in  swine  erysipelas  swine 
plague  and  hog  cholera.  In  view  of  the  fact  that  meat 
of  these  diseased  animals  has  frequently  been  eaten  for 
food  without  ever  having  incurred  any  impairment  or 
injury  to  man,  it  can  hardly  be  classed  as  injurious  to 
health.  In  individual  cases  however  the  following  should 
be  considered: 

"1.  The  entire  carcass  is  unfit  for  food  as  soon  as 
marked  substantial  changes  (congestion  of  blood,  serous 
infiltration,  degeneration,  yellow  discoloration)  of  the 
musculature  or  fatty  tissue  are  observed  or  when  marked 
emaciation  has  occurred. 

1  Udelman,  Meat  Hygiene  (English  translation  by  Mohler  and 
Eichhorn;  2d  edition,  1911). 

197 


198  HOG    CHOLEKA 

11 2.  In  all  other  cases,  with  the   exception  of  the 
chronic  forms  of  swine  plague  and  the  sequelae  of  this 
disease  and  those  of  hog  cholera,  the  carcass  in  all  of 
these  diseases  is  to  be  considered  fit  for  food  but  subject 
to  certain  conditions.     For  veterinary  sanitary  reasons, 
and  partly  in  consideration  of  the  causative  agents  in 
the  blood  of  swine  erysipelas,  swine  plague  and  the  acute 
forms  of  hog  cholera,  the  meat  and  fat  are  to  be  boiled, 
steamed  (rendered  into  lard)  or  pickled.    The  portions 
affected  by  the  disease  should  be  condemned. 

11 3.  In  case  of  slow  chronic  forms  of  swine  plague 
without  disturbance  of  the  general  condition,  or  sequelae 
of  this  disease  (adhesions,  cicatrices,  capsulated  caseated 
areas  etc.)   or  of  hog  cholera    (caseation  of  mesenteric 
lymph  glands,  adhesions  of  intestines,  formation  of  cica- 
trices in  the  intestinal  mucosa)  only  the  affected  portions 
of  the  meat  are  to  be  condemned  and  destroyed.     The 
remainder  of  the  carcass  is  fit  for  feed  without  any  re- 
striction. ' ' 


It  will  be  observed  that  swine  plague  and  swine 
erysipelas  are  governed  by  the  same  general  con- 
siderations that  apply  to  hog  cholera.  In  view  of 
the  fact  that  swine  plague  occurs  most  frequently 
as  a  complication  of  hog  cholera  as  well  as  of  the 
fact  that  rapid  differentiation  of  all  three  dis- 
eases based  on  abattoir  examinations  alone  is  not 
possible,  it  is  fortunate  indeed  that  these  diseases 
run  so  nearly  parallel  in  their  relation  to  meat 
inspection. 

From  the  excerpt  from  Edelmann  we  glean  the 
following  essential  considerations:  first,  the  fit- 
ness of  the  meat  for  human  food  is  based  on  patho- 


HOG    CHOLERA   AND    MEAT   INSPECTION  199 

logical  changes  in  the  meat  itself,  and  is  not  deter- 
mined by  the  probable  presence  or  absence  of  the 
causative  agents  of  hog  cholera,  swine  plague  or 
swine  erysipelas ;  second,  carcasses  of  hogs  which 
before  slaughter  were  obviously  suffering  with 
any  one  of  the  three  diseases,  may,  in  the  absence 
of  extensive  pathological  changes  in  the  meat  it- 
self be  passed  for  human  food,  but  for  veterin- 
ary sanitary  reasons  it  should  be  boiled,  rendered 
or  pickled  in  order  to  destroy  causative  agents  of 
either  of  the  three  animal  diseases  which  it  may 
contain. 

A  review  of  these  facts  leads  logically  to  the 
conclusion  that  as  far  as  hog  cholera  is  concerned 
there  is,  and  can  be,  no  sharp  line  of  demarcation 
between  carcasses  that  are  fit  for  human  food  and 
those  which  are  unfit,  because  it  has  not  been 
shown  that  hog  cholera  virus  is  injurious  to  man. 
The  more  important  phase  of  meat  inspection  as 
it  applies  to  hog  cholera  centers  around  the  de- 
cision which  determines  whether  a  particular  car- 
cass requires  special  treatment  (boiling,  render- 
ing or  pickling),  in  order  that  parts  of  it  may  not 
subsequently  infect  other  swine.  Edelmann  states 
clearly  the  need  for  a  distinction  between  the  fit 
and  the  unfit  based  solely  on  veterinary  sanitary 
reasons,  but  he  is  silent  as  to  how  this  distinc- 
tion is  to  be  made. 

The  U.  S.  Bureau  of  Animal  Industry  meat  in- 


200  HOG    CHOLERA 

spection  regulations  are  much  more  specific  in 
regard  to  the  manner  in  which  the  distinction  be- 
tween the  fit  and  the  unfit  shall  be  drawn,  but  the 
distinction  is  based  wholly  on  considerations  deal- 
ing with  the  fitness  of  the  meat  for  human  food. 
Veterinary  sanitary  considerations,  which  would 
include  atempts  to  require  cooking  or  rendering 
of  all  carcasses  which  contain  hog  cholera  virus, 
do  not  enter  in.  The  parts  of  these  regulations 
which  refer  specifically  to  hog  cholera  read  as  fol- 
lows: 

"  Regulation  9,  section  2,  paragraph  2.  All  hogs 
plainly  showing  on  ante-mortem  inspection  that  they  are 
affected  with  either  hog  cholera  or  swine  plague  shall  be 
marked  'U.  S.  condemned'  and  disposed  of  in  accordance 
with  section  8  of  this  regulation. 

"Regulation  9,  section  2,  paragraph  3.  If  a  hog  has 
a  temperature  of  106°  F.  or  higher,  and  if  it  is  of  a 
lot  in  which  there  are  symptoms  of  either  hog  cholera 
or  swine  plague,  in  case  of  doubt  as  to  the  cause  of  the 
high  temperature,  after  being  marked  for  identification, 
it  may  be  held  for  a  reasonable  time,  under  supervision 
of  an  inspector,  for  further  observation  and  taking  of 
temperature.  Any  hog  so  held  shall  be  reinspected  on 
the  day  it  is  slaughtered.  If  upon  such  reinspection, 
or,  when  not  held  for  further  observation  and  taking  of 
temperature,  then  on  the  original  inspection,  the  hog  has 
a  temperature  of  106°  F.  or  higher,  it  shall  be  condemned 
and  disposed  of  in  accordance  with  section  8  of  this 
regulation. 

"Regulation  9,  section  2,  paragraph  6.  All  animals 
which,  on  ante-mortem  inspection,  do  not  plainly  show, 
but  are  suspected  of  being  affected  with,  any  disease  or 


HOG    CHOLERA   AND    MEAT    INSPECTION  201 

condition  that,  under  these  regulations,  may  cause  con- 
demnation, in  whole  or  in  part,  on  post-mortem  inspec- 
tion, shall  be  so  marked  as  to  retain  their  identity  as 
suspects  until  final  post-mortem  inspection,  when  the  car- 
casses shall  be  marked  and  disposed  of  as  provided  else- 
where in  these  regulations,  or  until  disposed  of  in  ac- 
cordance with  section  7  of  this  regulation. 

'  Regulation  9,  section  4,  paragraph  1.  All  hogs,  even 
though  not  themselves  marked  as  suspects,  which  are  of 
lots  one  or  more  of  which  have  been  condemned  or 
marked  as  suspects  under  section  2  of  this  regulation 
for  either  hog  cholera  or  swine  plague,  shall  so  far  as 
possible  be  slaughtered  separately  and  apart  from  all 
other  animals  passed  on  ante-mortem  inspection. 

"Regulation  9,  section  7,  paragraph  3.  A  hog  sus- 
pected of  being  affected  with  hog  cholera  or  swine  plague 
may  be  set  apart  and  held,  under  bureau  supervision, 
for  treatment  with  anti-hog-cholera  serum.  If  at  the 
expiration  of  the  treatment  period  the  animal  upon 
examination  is  found  to  be  free  from  disease  it  may  be 
released  for  any  purpose. 

"Regulation  9,  section  8.  Except  as  hereinafter  pro- 
vided in  this  section,  animals  marked  'U.  S.  condemned' 
shall  be  killed  by  the  establishment,  if  not  already  dead, 
and  shall  not  be  taken  into  an  establishment  to  be 
slaughtered  or  dressed;  nor  shall  they  be  conveyed  into 
any  department  of  the  establishment  used  for  edible 
products;  but  they  shall  be  disposed  of  and  tanked  in 
the  manner  provided  for  condemned  carcasses  in  regula- 
tion 14.  The  'U.  S.  condemned'  tag  shall  not  be  re- 
moved from,  but  shall  remain  on,  the  animal  when  it 
goes  into  the  tank.  The  number  of  such  tag  shall  be 
reported  to  the  inspector  in  charge  by  the  bureau  em- 
ployee who  affixed  it,  and  also  by  the  bureau  employee 
who  supervises  the  tanking  of  the  animal,  provided, 
that  any  animal  condemned  on  account  of  hog  cholera 
and  swine  plague,  as  prescribed  in  paragraph  1,  2, 


202  HOG   CHOLEKA 

or  3  of  section  2  of  this  regulation,  may  be  set  apart 
and  held,  under  bureau  supervision,  for  treatment  with 
anti-hog-cholera  serum,  the  requirement  that  such  ani- 
mal shall  be  killed  shall  be  held  in  abeyance  to  await 
the  result  of  the  treatment.  If  at  the  expiration  of 
the  treatment  period  the  animal  upon  examination  is 
found  to  be  free  from  disease,  the  'U.  S.  Condemned' 
tag  shall  be  removed  and  the  animal  released  for  any 
purpose. " 

Post-mortem  inspection. 

"Regulation  11,  section  4,  paragraph  1.  The  car- 
casses of  all  hogs  marked  as  suspects  on  ante-mortem 
inspection  shall  be  given  careful  post-mortem  inspection ; 
and  if  it  appears  that  they  are  affected  with  either  acute 
hog  cholera  or  swine  plague  they  shall  be  disposed  of 
in  accordance  with  paragraph  2  of  this  section. 

"Regulation  11,  section  4,  paragraph  2.  Carcasses  of 
hogs  that  show  acute  and  characteristic  lesions  of  either 
hog  cholera  or  swine  plague  in  any  organ  or  tissue,  other 
than  the  kidneys  or  lymph  glands,  shall  be  condemned. 
Inasmuch  as  lesions  resembling  those  of  hog  cholera  or 
swine  plague  occur  in  the  kidneys  and  lymph  glands  of 
hogs  not  affected  with  hog  cholera  or  swine  plague, 
carcasses  of  hogs  in  the  kidneys  or  lymph  glands  of 
which  appear  any  lesions  resembling  lesions  of  hog  chol- 
era or  swine  plague — shall  be  carefully  further  in- 
spected for  corroborative  lesions.  On  such  further  in- 
spection— 

"(a)  If  the  carcass  shows  such  lesions  in  the  kid- 
neys, or  in  the  lymph  glands  or  both,  accompanied  by 
characteristic  lesions  in  some  other  organ  or  tissue, 
then  all  lesions  shall  be  regarded  as  those  of  hog  cholera 
or  swine  plague,  and  the  carcass  shall  be  condemned. 

"(&)  If  the  carcass  shows  in  any  organ  or  tissue, 
other  than  the  kidneys  or  lymph  glands,  lesions  of  either 


HOG   CHOLERA  AND   MEAT   INSPECTION  203 

hog  cholera  or  swine  plague  which  are  slight  or  limited 
in  extent,  it  shall  be  passed  for  sterilization  in  accord- 
ance with  regulation  15. 

"  (c)  If  the  carcass  shows  no  identification  of  either 
hog  cholera  or  swine  plague  in  any  organ  or  tissue  other 
than  the  kidney  or  lymph  glands  it  shall  be  passed  for 
food  unless  some  other  provision  of  these  regulations 
requires  a  different  disposal." 

For  years  it  has  been  a  common  practice  among 
swine  raisers  to  consign  hogs  to  market  as  soon  as 
hog  cholera  appeared  among  them,  and  even  at 
the  present  day,  when  an  effective  preventive  of 
the  disease  is  at  hand,  the  custom  still  prevails. 
If  an  entire  herd  consists  of  hogs  nearing  com- 
pletion of  the  fattening  period,  and  if  cholera  is 
recognized  as  soon  as  it  appears,  the  loss  to  the 
feeder  is  not  heavy.  He  promptly  markets  all 
hogs  that  are  apparently  well,  leaving  behind  the 
few  that  are  visibly  sick.  If,  though,  a  herd  in- 
cludes sows,  pigs  and  shoats  which  cannot  be  mar- 
keted to  advantage,  or  if  it  consists  of  pure-bred 
animals,  heavy  and  unnecessary  loss  must  be  ac- 
cepted in  consigning  it  to  market.  Unfortunately 
the  loss  is  not  confined  to  the  man  who  ships  the 
infected  hogs.  His  herd  becomes  a  menace  to 
others  in  the  vicinity  as  it  is  driven  to  the  nearest 
loading  station,  and  it  helps  to  perpetuate  the  in- 
fection which,  existing  in  practically  all  large  pub- 
lic stockyards  in  the  country,  threatens  all  cholera 
susceptible  swine  not  intended  for  immediate 


204  HOG   CHOLEKA 

slaughter.  Nor  is  the  danger  terminated  when 
the  hogs  reach  the  shambles.  An  impression  pre- 
vails that  in  establishments  where  meat  inspec- 
tion regulations  are  in  force,  carcasses  that  con- 
tain hog  cholera  virus  are  condemned,  and  those 
that  do  not  contain  it  are  passed  for  food.  This 
is  not  the  case.  Many  carcasses  that  contain  the 
virus  readily  pass  inspection,  and  although  they 
are  perfectly  fit  for  human  food,  trimmings  from 
them  regularly  find  their  way  into  garbage,  and 
when  this  is  fed  to  susceptible  hogs,  they,  in  turn, 
contract  disease.  It  is  a  vicious  cycle,  and  one 
very  difficult  to  break. 

When  a  consignment  of  hogs  from  a  cholera 
infected  herd  reaches  an  establishment  where  fed- 
eral meat  inspection  regulations  are  in  force  it  is 
first  subjected  to  ante-mortem  inspection.  With 
respect  to  hog  cholera  it  may  contain  five  classes 
of  hogs:  first,  dead  hogs;  these  are  condemned 
and  tanked:  second,  hogs  that  show  undoubted 
symptoms  of  cholera;  these  also  are  condemned 
and  tanked:  third,  those  that  show  suspicious 
symptoms  and  temperatures  below  106°  F.,  these 
are  slaughtered ;  carcasses  that  show  hog  cholera 
lesions  are  condemned  or  passed  for  sterilization 
according  to  the  extent  of  the  lesions;  those  that 
show  no  lesions  are  passed  for  food :  fourth,  hogs 
apparently  normal,  and  those  which  show  suspi- 
cious symptoms,  having  temperatures  above  106° 


HOG   CHOLEBA   AND    MEAT   INSPECTION  205 

F. ;  these  are  condemned  or  isolated  for  further 
temperature  records;  in  case  further  tempera- 
tures are  taken  the  animals  are  condemned  if  the 
readings  are  still  above  106°;  otherwise  they  fall 
into  class  three  or  class  five :  fifth,  apparently  nor- 
mal hogs  that  show  temperatures  below  106°; 
these  pass  ante-mortem  inspection  and  post-mor- 
tem as  well  if  they  do  not  show  lesions  of  hog  chol- 
era in  organs  other  than  the  kidneys  or  lymph 
glands. 

Let  us  consider  the  individual  hog.  Briefly 
stated,  the  requirements  in  order  that  it  may  pass 
inspection  are  that  it  shall  not  show  conclusive 
symptoms  of  hog  cholera,  it  shall  not  show  sus- 
picious symptoms  plus  hog  cholera  lesions,  it  shall 
not  maintain  repeated  temperature  readings  above 
106°  F.,  and  regardless  of  ante-mortem  findings 
the  carcass  shall  not  on  post-mortem  show  hog 
cholera  lesions  in  organs  other  than  the  kidneys  or 
lymph  glands.  What  are  the  chances  for  car- 
casses that  contain  hog  cholera  virus  to  pass  in- 
spection ? 

This  question  is  best  answered  by  considering 
the  average  case  of  hog  cholera.  Let  us  suppose 
that  a  hog  becomes  infected  to-day.  According  to 
Dorset,  "Bepeated  experiments  have  shown  that 
the  blood  of  pigs  that  have  previously  been  in- 
oculated with  the  virus  of  cholera  becomes  infec- 
tious for  others  within  twenty-four  hours;  the 


206  HOG    CHOLERA 

urine  and  f eces  contain  the  virus  usually  in  forty- 
eight  hours,  and  the  secretions  of  the  eyes  and 
nose  become  infectious  by  the  third  day  follow- 
ing infection:  therefore  these  experiments  show 
that  infected  pigs  are  capable  of  transmitting 
the  disease  before  they  themselves  show  any  visi- 
ble illness."  l 

Thus  the  blood  and  therefore  the  meat  of  a  hog 
infected  to-day  will  to-morrow  contain  hog  cholera 
virus  sufficient  to  infect  others,  but  there  will  be 
neither  symptoms,  temperature  readings  nor  le- 
sions to  cause  its  condemnation.  The  same  will 
be  true  on  the  second,  third  and  fourth  days  fol- 
lowing infection,  but  from  that  time  on  we  may  at 
any  time  expect  developments  that  would  cause 
condemnation.  These  may,  though,  be  delayed 
several  days  longer.  There  is  a  time,  at  least 
three  days  on  an  average,  in  the  lives  of  practi- 
cally all  hogs  affected  with  acute  hog  cholera  when 
they  will  pass  inspection  and  when  bits  of  pork 
from  their  carcasses  will  infect  other  swine  to 
which  they  are  fed.  This  interval  varies  from 
one  or  two  to  several  days,  and  is  measured, 
roughly,  by  the  time  required,  after  the  first 
twenty-four  hours  following  infection,  for  the 
temperature  to  rise  to  106°  F.,  or  for  conclusive 
symptoms  or  extensive  cholera  lesions  to  appear. 

1Keport  of  the  chief  of  the  U.  S.  Bureau  of  Animal  Industry 
for  the  year  ending  June  30,  1917. 


HOG    CHOLERA   AND    MEAT    INSPECTION  207 

With  these  facts  in  mind,  let  us  again  consider 
the  farm  herd  from  which  cholera  infected  hogs 
are  shipped.  Often  a  considerable  number  must 
die  before  the  owner  will  admit,  even  to  himself, 
that  he  is  dealing  with  hog  cholera.  Then  there 
is  the  delay  incident  to  securing  transportation, 
and  there  are  many  hours  during  which  infected 
and  sound  animals  are  crowded  together  in  a  stock 
car.  Finally,  after  the  hogs  reach  the  yards  there 
is  an  additional  delay  of  several  hours  or  even 
several  days  before  they  are  killed.  Any  person 
familiar  with  hog  cholera  knows  that  in  such  a 
consignment  a  great  majority  of  the  hogs  become 
infected  before  they  are  killed  and  any  person 
familiar  with  present-day  meat  inspection  regula- 
tions knows  that  under  such  circumstances  the 
vast  majority  of  the  infected  animals  will  pass  in- 
spection. The  hogs  have  every  chance  to  become 
infected  but  the  disease  does  not  have  time  to 
develop  sufficiently  to  cause  their  condemnation. 

The  practice  of  marketing  swine  herds  as  soon 
as  cholera  appears  is  no  longer  necessary.  It 
rarely  profits  the  man  who  follows  it,  and  it  per- 
petuates hog  cholera,  working  great  harm  to  the 
swine  industry.  Before  the  discovery  of  protec- 
tive serum  a  herd  of  hogs  once  infected  with  chol- 
era became  a  total  loss  unless  some  of  the  animals 
could  be  salvaged  by  slaughter.  With  the  plenti- 
ful supply  of  serum  now  available  an  infected  herd 


208  HOG   CHOLERA 

can  safely  and  profitably  be  kept  at  home.  All 
that  is  required  is  prompt  reporting,  prompt  diag- 
nosis and  prompt  serum  treatment.  With  few 
exceptions  serum  will,  at  any  given  time,  save  all 
hogs  which  are  not  at  that  time  already  danger- 
ous carriers  of  hog  cholera  virus. 

In  the  United  States,  during  the  decade  ending 
in  1911  approximately  18,000  hogs  were  condemned 
annually  on  account  of  hog  cholera.  In  1914 
the  number  reached  a  total  of  116,000;  in  1917, 
33,000.  According  to  Bureau  of  Animal  Industry 
estimates,  40  per  cent  of  the  pork  which  is  killed 
and  15  per  cent  of  that  which  is  marketed  in  the 
United  States  is  slaughtered  on  farms  or  in  abat- 
toirs in  which  no  inspection  is  maintained.  Judg- 
ing from  my  study  of  the  situation  as  a  whole,  my 
belief — which  I  would  be  reluctant  to  express  in 
concrete  terms  if  it  were  not  essential  to  convey  at 
least  an  approximate  idea  of  existing  conditions — 
is  that  in  the  country  at  large,  for  each  hog  which 
is  condemned  for  cholera,  at  least  three  virus-con- 
taining carcasses  pass  or  evade  inspection.  What 
becomes  of  them  subsequently? 

Each  infected  carcass  possesses  almost  infinite 
possibilities  in  regard  to  its  final  distribution. 
Whether  the  pork  reaches  the  consumer  in  the 
form  of  hams,  shoulders,  or  bacon,  or  whether  it 
is  fresh,  refrigerated  or  cured,  we  should  not  lose 
sight  of  the  fact  that  it  actually  contains  unlabeled 


HOG    CHOLERA   AND    MEAT    INSPECTION  209 

hog  cholera  virus,  and  that  uncooked  portions  of 
it  fed  to  susceptible  hogs  will  produce  cholera. 

Of  the  various  preserving  and  preparing  proc- 
esses to  which  pork  is  subjected  before  being 
sent  to  the  consumer,  only  one  that  we  know  of — 
cooking — is  certain  to  destroy  hog  cholera  virus 
which  it  may  contain.  According  to  extensive 
experiments  *  which  we  have  carried  out  the  virus 
lives  in  fresh  meat  until  decomposition  sets  in,  it 
is  not  affected  by  prolonged  refrigeration,  and  a 
representative  sugar  curing  and  smoking  process 
killed  it  in  only  43  per  cent  of  the  tests  made. 

So  far  we  have  dealt  chiefly  with  the  facts  sur- 
rounding hog  cholera  and  meat  inspection  as  they 
have  been  determined  by  exact  scientific  methods 
and  recorded  data.  It  remains  to  be  added  that 
clinical  observations  are  entirely  in  accord  with 
these  facts.  We  hear  of  one  outbreak  of  hog  chol- 
era in  Canada,  and  it  is  traced  to  a  consignment 
of  infected  hams ;  we  hear  of  another  in  a  remote 
lumber  camp  in  the  Adirondacks  where  hogs  are 
kept  to  consume  the  kitchen  refuse;  and  of  still 
another  on  an  inaccessible  farm  in  Nevada  follow- 
ing purchases  of  market  pork.  These  are  merely 
representative  instances.  At  least  90  per  cent  of 
the  outbreaks  we  encounter  in  New  York  can  be 
traced  to  no  other  source  than  infected  pork  trim- 

1  Report  of  New  York  State  Veterinary  College  1915-1916,  page 
60. 


210  HOG    CHOLERA 

mings  in  garbage,  and  in  other  Eastern  states 
the  situation  is  essentially  the  same.  Torrance  l 
reports  similar  conditions  in  Canada.  In  the 
Southern  and  central  states  a  much  smaller  pro- 
portion of  herds  become  infected  through  the 
agency  of  pork  trimmings  from  carcasses  that 
contain  hog  cholera  virus,  but  even  in  these  sec- 
tions there  is  ample  evidence  that  the  first  infec- 
tion in  many  outbreaks  takes  origin  in  this  man- 
ner. Once  established  in  territory  that  supports 
a  dense  swine  population,  the  .disease  spreads 
rapidly  through  many  other  agencies. 

Meat  inspections  in  field  outbreaks  of  hog 
cholera.  The  practicing  veterinarian  who  is 
called  to  handle  a  farm  herd  infected  with  hog 
cholera  very  frequently  is  questioned  regarding 
killing  and  marketing  all  animals  that  remain  ap- 
parently well.  How  is  he  to  advise  his  clients'? 

Disregarding,  for  the  moment,  legal  and  sani- 
tary considerations,  and  thinking  only  of  the  plan 
that  will  cause  our  clients  the  least  immediate 
financial  loss,  we  will  find  relatively  few  instances 
where  immediate  slaughter  can  be  advised. 
These  occur  principally  in  herds  of  feeders  about 
ready  for  market  anyhow,  and  in  herds  in  which 
the  disease  has  progressed  so  far  that  protective 
serum  offers  very  little  hope.  In  either  case  the 

1 '  *  Garbage  Feeding  in  Eolation  to  the  Control  of  Hog  Cholera, ' J 
Journal  of  the  American  Veterinary  Medical  Association,  Octo- 
ber, 1921,  p.  22. 


HOG   CHOLEEA   AND   MEAT   INSPECTION  211 

hogs  are  worth  more  as  pork  than  they  will  ever 
again  be  worth  on  foot,  but  here  legal  and  sanitary 
considerations  enter  in,  and  it  is  only  where  the 
state  law  provides  for  slaughter  under  inspection 
and  where  provision  can  be  made  to  minimize  the 
danger  to  other  herds  that  may  result  from  mar- 
keting the  pork,  that  slaughtering  is  to  be  ad- 
vised. 

New  York,  for  instance,  has  a  law  which  permits 
killing  under  inspection  from  herds  infected  with 
cholera,  but  it  is  only  at  institutions  and  on  farms 
where  the  pork  will  not  be  placed  on  the  open  mar- 
ket that  we  have  advised  such  a  course.  We  hab- 
itually follow  the  plan  of  explaining  the  situation 
to  our  client,  and  informing  him  that  he  has  a 
legal  right  to  kill,  but  that  he  has  at  the  same  time 
a  moral  obligation  to  protect  his  neighbor.  When 
we  offer  at  the  same  time  the  alternative  of  serum 
treatment,  giving  a  prognosis  as  nearly  exact  as  is 
possible,  there  are  few  who  will  not  decide  to  use 
serum  or  who  will  not  profit  by  doing  so.  Indeed 
in  just  one  instance  that  we  recollect  has  one  of 
our  clients  elected  to  take  shelter  under  the  law 
and  disregard  his  neighbor.  This  man  had  a  herd 
consisting  originally  of  about  four  hundred  hogs. 
Cholera  appeared,  but  he  refused  to  accept  our 
diagnosis.  Finally  when  his  herd  had  dwindled  to 
about  one  hundred  and  fifty  animals,  he  decided  to 
vaccinate.  It  was  a  forlorn  hope,  but  we  began 


212  HOG   CHOLERA 

taking  temperatures,  intending  to  administer  se- 
rum only  to  those  that  showed  readings  below  104° 
F.  After  numerous  trials  in  which  we  found  but 
a  negligible  number  of  readings  below  106°  F.,  we 
gave  up  the  attempt  and  returned  home.  Later 
we  were  informed  from  reliable  sources  that  imme- 
diately on  our  departure  about  seventy-five  hogs 
from  the  herd  were  shipped  to  market  and  that  the 
majority  of  them  passed  federal  inspection.1  The 
man  in  this  instance  received  more  for  the  hogs 
than  he  would  have  received  had  he  administered 
serum  to  all  of  them  as  an  eleventh-hour  mea- 
sure, but  he  received  infinitely  less  than  would 
have  fallen  to  his  lot  had  he  treated  the  herd  with 
protective  serum  at  the  time  when  he  was  first 
warned  of  the  danger. 

In  those  instances  in  which  the  practicing  veter- 
inarian is  called  to  inspect  hogs  that  are  being 
slaughtered  from  cholera-infected  herds,  the  fed- 
eral meat  inspection  regulations 2  should  be  se- 
lected as  a  convenient  guide,  but  unless  it  is  so 
specified  by  state  law,  they  are  not  to  be  regarded 
as  inflexible  or  final.  The  practitioner  must 

*  This  must  not  be  construed  as  a  criticism  of  the  administration 
of  the  federal  meat  inspection  regulations.  It  is  merely  a  rather 
striking  example  of  the  fact  that  the  regulations,  admirably 
formulated  and  enforced  to  protect  human  health  and  human  life, 
cannot  be  relied  on  to  eliminate  from  our  markets  swine  carcasses 
that  contain  hog  cholera  virus. 

a  The  paragraphs  that  relate  to  hog  cholera  appear  near  the 
beginning  of  this  chapter. 


HOG   CHOLEKA   AND   MEAT   INSPECTION  213 

adapt  his  decisions  to  the  conditions  under  which 
he  is  working.  If  he  knows  that  the  pork  is  to  be 
sold  in  the  open  market  where  it  will  become  the 
potential  cause  of  future  outbreaks,  he  cannot  be 
justly  criticized  if  he  is  relatively  severe  in  his 
decisions ;  on  the  other  hand,  if  the  pork  is  to  be 
retained  at  the  place  where  it  is  killed,  as  it  is  on 
some  institution  farms,  for  instance,  rather  ex- 
tensive hog  cholera  lesions  should  be  required  in 
order  to  condemn.  Carcasses  that  are  not  deemed 
fit  for  pork  can  be  partially  salvaged  in  the  form 
of  lard. 

When  slaughter  on  the  farm  is  decided  on, 
ante-mortem  inspection  should  consist  first  of  ob- 
serving the  hogs  before  they  are  disturbed,  and  re- 
jecting any  that  obviously  are  suffering  with  hog 
cholera.  Then  temperatures  may  be  taken  of 
those  that  remain  and  any  that  show  readings 
above  106°  F.  should  be  condemned  or  put  aside 
for  subsequent  readings.  Later  if  they  show  tem- 
peratures below  106°  F.  they  may  be  slaughtered 
and  post-mortem  findings  will  determine  whether 
the  carcass  shall  be  passed  or  condemned.  In  case 
the  weather  is  very  warm,  or  if  it  is  necessary 
to  excite  the  animals  unduly  in  taking  tempera- 
tures, one  may  secure  more  accurate  information 
by  giving  them  a  limited  quantity  of  feed  and  re- 
jecting those  that  do  not  remain  at  the  trough  and 
eat  greedily.  Nearly  all  will  come  to  the  trough  at 


214  HOG   CHOLEBA 

first,  but  those  that  are  suffering  most  with  chol- 
era will  soon  return  to  the  nest. 

Principles  governing  post-mortem  inspection 
have  already  been  discussed.  Briefly,  extensive 
changes  in  the  meat  or  fat  should  cause  condemna- 
tion. Hog  cholera  lesions  in  the  kidneys  and 
lymph  glands  do  not  condemn  the  carcass,  al- 
though in  cholera-infected  herds  such  lesions  prac- 
tically always  establish  its  status  as  a  virus  car- 
rier. Carcasses  that  show  hog  cholera  lesions  in 
the  kidneys,  lymph  glands  and  other  organs  as  well 
are  not  used  for  pork,  but  if  the  lesions  are  slight 
in  extent  the  fat  may  be  rendered  into  lard.  Most 
hogs  that  appear  well  on  foot  pass  post-mortem 
inspection  as  well. 

Garbage  Feeding 

Intimately  bound  up  with  meat  inspection  as  it 
applies  to  hog  cholera  is  the  subject  of  garbage 
feeding.  As  we  have  already  shown  this  prac- 
tice is  the  final 'link  in  the  chain  which  is  respon- 
sible for  the  introduction  of  cholera  into  so  many 
herds  of  hogs.  If  meat  inspection  regulations  be- 
come more  stringent,  garbage  feeding  becomes 
less  hazardous;  if  they  become  less  stringent,  or 
if  they  are  neglected  altogether  the  risks  from  in- 
fected pork  trimmings  in  garbage  increase.  In 
any  event,  chance  alone  decides  when  any  par  tic- 


HOG   CHOLERA   AND    MEAT   INSPECTION  215 

ular  herd  that  subsists  on  garbage  will  contract 
hog  cholera.  The  larger  the  herd,  the  greater 
the  supply  of  garbage  necessary  to  maintain  it, 
and  the  more  certain  it  is  to  become  infected. 

In  earlier  years  feeding  garbage  to  hogs  has 
produced  the  most  surprising  and  contrasting  re- 
sults. Its  feeding  value  has  long  been  well  known, 
and  men  who  were  tempted  to  utilize  it  in  feeding 
hogs  usually  began  the  practice  on  a  small  scale. 
If  hog  cholera  did  not  'happen  to  reach  the  herd 
during  the  first  year,  the  financial  returns  were 
usually  gratifying  beyond  expectations,  and  the 
hog  raiser  enthusiastically  increased  the  size  of 
his  herd — at  the  same  time  multiplying  its  chances 
to  become  infected  with  cholera.  Thus  a  common 
experience  was  for  the  breeder  to  have  the  savings 
of  one  or  more  years  invested  entirely  in  hogs 
when  cholera  finally  reached  his  herd  and  de- 
stroyed it. 

Various  preventives  of  the  disease  incident  to 
garbage  feeding  were  advertised,  and  magic  for- 
mulas were  passed  around  by  word  of  mouth. 
Perhaps  one  man  fed  salt  and  sulphur  to  his  hogs 
and  did  not  lose  a  single  one;  another  neglected 
to  do  this  and  his  entire  herd  was  destroyed. 
Could  any  proof  be  more  convincing!  But  the 
law  of  chance  was  still  in  operation,  and  hog  chol- 
era was  relentlessly  striking  down  one  herd  after 
another,  including  those  which  received  the  lauded 


216  HOG   CHOLERA 

preventives  with  those  that  did  not,  in  a  wholly 
impartial  manner. 

There  was  a  belief  that  garbage  in  itself  pro- 
duced the  disease,  and  there  was  divided  opinion 
as  to  whether  it  was  dietetic  in  nature  or  whether 
it  was  really  hog  cholera.  The  trouble  was 
thought  by  some  to  be  due  to  a  variety  of  causes — 
as  in  truth  it  was  to  a  limited  extent— but  when 
anti-hog-cholera  serum  was  brought  into  use  it 
was  found  that  this  product  prevented  most  rap- 
idly-fatal infectious  disease  which  had  formerly 
plagued  the  garbage  feeder 's  herd.  Also  the  ad- 
vent of  kitchen  sinks  and  drains  eliminated  soap 
poisoning  due  to  dish  water  which  was  formerly 
included  in  garbage.  These  two  advances  have 
placed  garbage  feeding  on  a  relatively  safe 
basis. 

The  collection  and  disposal  of  city  garbage  is 
a  complex  and  exacting  process,  and  staggering 
sums  are  paid  annually  for  this  service.  Disposal 
plants  cost  huge  sums  of  money  as  original  invest- 
ments, and  coal,  labor  and  upkeep  incident  to  their 
operation  require  a  heavy  and  continuous  outlay. 
One  city  of  100,000  that  we  know  of — and  it  is  no 
exception — was  until  recently  incurring  the  ex- 
pense of  collecting  its  garbage  and  hauling  it  three 
miles  to  a  disposal  plant,  and  it  was  also  operating 
the  plant  at  an  annual  expense  of  $40,000.  The 
garbage  was  burned  and  there  was  no  salvage,  as 


HOG   CHOLEKA  AND   MEAT   INSPECTION  217 

there  is  in  some  disposal  plants,  in  the  form  of 
grease,  tankage  and  bones. 

Viewing  the  subject  of  garbage  feeding  from 
the  standpoint  of  the  municipality  it  may  be  said 
that  in  cities  of  less  than  100,000  feeding  is  by 
far  the  most  economical  plan  of  disposal,  and  ex- 
perience will  probably  prove  that  the  same  rule 
holds  good  for  larger  cities.  If  provisions  are 
made  for  feeding,  no  city  of  less  than  100,000 
should  find  it  necessary  to  pay  disposal  costs,  and 
many  should  be  able  to  offset  in  some  degree, 
collection  costs  as  well.  Cities  that  elect  to  dis- 
pose of  their  garbage  by  feeding  may  maintain 
piggeries  as  a  municipal  function,  or  they  may 
provide  by  contract  for  collection  and  disposal. 
We  believe  the  most  satisfactory  plan  is  for  the 
city  to  collect  the  garbage  and  deliver  it  to  the 
contractor's  piggery  or  to  a  specified  loading 
station. 

Long  term  contracts  with  optional  renewals  on 
the  part  of  the  contractor  are  the  only  ones  that 
will  prove  satisfactory  when  the  plan  is  to  feed 
the  garbage.  No  man  can  afford  to  build  adequate 
quarters  for  large  numbers  of  hogs  unless  there  is 
assurance  of  a  constant  supply  of  feed  during  a 
term  of  years.  Short  term  contracts  are  respon- 
sible in  large  measure  for  the  fact  that  the  gar- 
bage feeder's  establishment  is  so  often  a  public 
nuisance.  He  does  not  have  time  to  organize  his 


218  HOG   CHOLEEA 

feeding  operations,  lie  cannot  invest  in  good  equip- 
ment that  will  have  to  be  sold  at  a  loss  as  soon  as 
his  contract  terminates,  and  there  is  not  sufficient 
time  for  the  enterprise  itself  to  yield  profits  that 
may  be  returned  to  it  in  the  form  of  equipment. 

When  a  city  wishes  to  let  its  garbage  contract 
to  the  best  advantage  it  should  agree  to  give  the 
contractor  all  the  municipal  garbage,  and  it  should 
provide  ordinances  that  require  its  drainage  and 
the  exclusion  of  tin  cans,  broken  bottles  and  the 
like.  Collections  should  be  required  at  least  once 
a  week  in  winter  and  twice  in  summer.  A  five- 
year  contract  which  the  contractor  can  renew  at 
his  option  if  he  discharges  his  obligations,  is  satis- 
factory, and  will  serve  to  entice  reliable  con- 
tractors. 

Municipal  piggeries  are  successful  sometimes, 
but  changing  city  administrations  are  not  always 
to  their  best  advantage.  Sooner  or  later  self- 
styled  "business  men"  are  likely  to  be  charged 
with  their  general  supervision,  and  in  formulat- 
ing business  rules  for  their  subordinates  they 
themselves  are  likely  to  ignore  essential  natural 
laws  governing  swine  husbandry  and  the  handling 
of  swine  diseases.  Business  principles  must  of 
course  be  observed,  but  they  must  be  made  to 
dovetail  with  principles  that  conserve  the  health 
of  the  swine  and  provide  each  day  for  their  intelli- 
gent care. 


HOG   CHOLEEA   AND   MEAT   INSPECTION"  219 

Garbage  varies  greatly  in  feeding  value,  but  as 
a  very  general  rule  one  ton  of  well  drained  city 
garbage  which  is  free  from  extraneous  matter  will 
feed  about  fifty  or  sixty  fattening  hogs,  causing 
them  to  gain  from  %  to  one  pound  each.  In  other 
words  one  ton  of  garbage  should  produce  about 
fifty  pounds  of  pork.  At  least  200  pounds  of  a 
good  grain  ration  is  required  to  produce  the  same 
gains.  Thus  as  far  as  the  public  at  large  is  con- 
cerned dumped  or  burned  garbage  represents  a 
great  and  avoidable  waste,  and  in  states  with 
large  urban  populations  this  waste  assumes  huge 
proportions. 

Veterinary  Supervision  of  Garbage-Fed  Herds 

Herds  of  hogs  fed  on  city  garbage  are  con- 
stantly threatened  with  cholera,  and  for  this  rea- 
son they  sooner  or  later  come  under  the  veteri- 
narian's care.  The  dangers  nowadays  are  fre- 
quently known  in  advance  and  hence  professional 
advice  is  sought  before  a  herd  is  assembled,  but 
many  feeders  are  still  ignorant  of  the  chances  they 
assume,  and  still  others  procrastinate  in  regard 
to  immunizing. 

When  a  veterinarian  is  consulted  before  a  herd 
is  assembled,  or  before  hog  cholera  appears  in  it 
he  can  render  service  of  a  high  order  if  he  is  fa- 
miliar with  disease  prevention  and  swine  hus- 
bandry methods.  He  also  assumes  considerable 


220  HOG   CHOLEKA 

responsibility,  for,  given  a  clean  herd  he  is  sup- 
posed to  know  how  to  keep  it  clean.  The  preven- 
tion or  handling  of  hog  cholera  in  herds  fed  on 
garbage  is  not  different  in  principle  from  han- 
dling the  disease  in  other  herds,  but  there  are 
several  difficulties  peculiar  to  the  garbage-fed 
herd  that  must  be  overcome.  These  difficulties  are 
so  closely  linked  up  with  methods  of  swine  hus- 
bandry that  all  must  be  considered  at  the  same 
time. 

Should  the  garbage  feeder  raise  or  purchase 
feeding  hogs !  Many  considerations  enter  in,  but 
as  a  general  rule  if  the  herd  is  to  be  relatively 
small,  say  less  than  500,  if  there  is  provision 
for  exercise  and  a  little  pasture,  if  warm  farrow- 
ing pens  can  be  provided,  and  if  a  supervisor  who 
thoroughly  underctands  swine  breeding  can  be  se- 
cured, the  ^est  plan  is  to  raise  the  pigs.  Under 
ordinary  conditions,  as  the  herd  is  increased  in 
size,  raising  the  pigs  becomes  relatively  less  feas- 
ible. The  question  of  proximity  to  a  good  mar- 
ket for  good  feeding  shoats  likewise  must  be  con- 
sidered, and  what  we  have  said  in  a  preceding 
chapter  in  regard  to  handling  feeder  hogs,  applies 
here  as  well.  Shoats  that  have  been  immunized 
on  the  farm  are  by  far  the  safest  purchase,  and 
susceptible  ones  that  can  be  purchased  from 
thrifty  farm  herds  may  be  immunized  without 
much  danger.  Purchase  of  stockyard  hogs  is  ad- 


HOG   CHOLERA   AND    MEAT   INSPECTION  221 

visable  at  times,  but  judicious  selection  and  care- 
ful handling  are  essential,  and  even  then  the  best 
professional  care  does  not  always  insure  against 
considerable  loss  from  hog  cholera  and  its  com- 
plications. 

When  it  is  desirable  to  purchase  feeding  shoats 
to  consume  garbage,  those  weighing  between  75 
and  120  pounds  are  most  desirable.  Although  it 
is  feasible  to  raise  the  very  best  pigs  on  garbage 
alone,  the  fact  remains  that  often  they  begin  to 
eat  it  well  and  put  on  rapid  gains  only  after  they 
have  attained  considerable  size.  It  is  likewise 
true  that  shoats  cannot  be  put  on  full  feed  as  rap- 
idly when  garbage  is  fed  as  they  can  when  their 
ration  consists,  of  grain,  hence  it  is  well  to  pur- 
chase rather  light  shoats  so  that  the  loss  of  time 
in  getting  them  started  can  be  made  up  by  a  rela- 
tively long  fattening  period. 

Except  when  cholera  immune  shoats  are  pur- 
chased from  the  farm  it  is  necessary  that  immu- 
nizing shall  take  place  before  or  immediately 
after  they  reach  the  feeder 's  yards,  and  thus  they 
must  often  undergo  the  resulting  reaction  before 
the  condition  known  in  the  fattening  pen  as  "full 
feed"  is  reached.  Special  care  is  necessary  not 
to  overfeed  at  this  time.  Efforts  to  crowd  the 
animals  beyond  their  capacity  may  aid  in  caus- 
ing "serum  breaks, "  and  do  injury  that  will  re- 
quire weeks  to  overcome.  ,  With  this  one  special 


222  HOG   CHOLEEA 

precaution  our  readers  are  referred  to  the  head- 
ing in  the  last  chapter  entitled  ' '  Handling  Feeder 
Hogs." 

It  is  in  raising  pigs  entirely  on  garbage  that 
the  greatest  care  is  required.  Numerous  pitfalls 
are  in  the  path  of  the  beginner,  and  it  is  a  quite 
general  rule  that  one  serious  disaster  is  necessary 
to  impress  him  with  the  necessity  for  avoiding 
neglect.  The  critical  period  in  a  pig 's  life  is  from 
weaning  time  until  he  reaches  a  weight  near  75 
pounds.  When  garbage  is  to  be  the  sole  feed  it 
is  a  great  mistake,  and  a  common  one,  for  the  pigs 
to  be  weaned  while  they  are  very  young.  The 
breeder  is  anxious  that  the  sow  shall  produce  an- 
other litter  as  soon  as  possible,  and  thus  it  is  not 
uncommon  for  weaning  to  take  place  when  the 
pigs  are  four  weeks  old,  or  a  trifle  more.  They 
are  then  too  young  to  gain  well  on  garbage  alone 
and  they  are  subject  to  various  dietary  troubles 
that  are  not  often  observed  in  pigs  weaned  later 
in  life.  One  good  litter  a  year  born  quite  early  in 
the  spring  and  nursed  until  the  pigs  are  eight  or 
even  twelve  weeks  of  age  is  more  profitable  than 
two  litters  weaned  too  young.  However  when 
warm  farrowing  pens  are  provided  it  is  not  neces- 
sary to  choose  between  one  litter  a  year,  and  two. 
The  sow  can  nurse  her  litter  the  required  time 
and  then  be  bred  at  the  first  period  of  heat  fol- 


HOG   CHOLERA   AND    MEAT   INSPECTION  223 

lowing  weaning  of  the  pigs  regardless  of  the  time 
of  year  that  farrowing  will  occur. 

When  the  pigs  are  weaned  too  young  "runts" 
are  common  among  them,  and  in  waiting  for  the 
animals  to  become  of  sufficient  size  to  receive  si- 
multaneous treatment  it  is  not  uncommon  for  the 
breeder  to  prolong  to  a  dangerous  degree  the  in- 
terval between  serum  alone  and  simultaneous 
treatments.  The  passive  immunity  due  to  the 
former  partially  disappears,  and  hog  cholera,  fre- 
quently of  an  atypical  and  subvirulent  type,  some- 
times appears  among  them.  Often  this  type  of  the 
disease  is  not  recognized  as  hog  cholera.  Pigs  in 
large  herds  require  earlier  serum  alone  treatment 
and  are  more  likely  to  require  two  treatments 
prior  to  the  final  serum-virus  administration  than 
are  those  in  smaller  herds.  This  is  because  of  the 
fact  that  in  large  herds  the  chances  for  infection 
are  so  great  that  the  virus  of  the  disease  must  be 
regarded  as  being  continuously  present. 

Pasture  and  abundant  room  for  exercise  are  of 
great  benefit  to  young  pigs  that  subsist  on  gar- 
bage. There  seems  to  be  a  general  fear  that  pigs 
will  "run  all  the  fat  off  them"  if  they  are  allowed 
generous  room  for  exercise.  We  have  repeatedly 
observed  the  effects  of  turning  pigs  from  cramped 
and  dirty  quarters  into  pastures  or  large  enclos- 
ures, and  the  change  has  always  been  in  their 


224  HOG    CHOLERA 

favor.  Granting  good  weather  conditions,  very 
young  pigs  that  become  exhausted  in  attempts  to 
follow  the  sow,  and  feeders  near  completion  of 
the  fattening  period  are  the  only  exceptions  to 
this  rule. 

There  is  a  tradition  that  hogs  grown  on  garbage 
from  generation  to  generation  become  accustomed 
to  it  and  consume  it  to  better  advantage.  For- 
merly we  were  inclined  to  regard  this  belief  as 
being  without  foundation  on  fact,  but  in  later 
years  we  have  seen  evidence  that  causes  us  to 
change  our  views.  It  is  certain  that  sows  pur- 
chased from  grain-fed  herds  and  required  to  sub- 
sist on  garbage  frequently  fail  to  farrow  large 
litters  in  the  spring  subsequent  to  the  change,  and 
while  this  may  often  be  explained  on  the  ground 
of  insufficient  exercise  and  overfat  condition,  this 
explanation  covers  only  a  portion  of  the  cases. 
If  we  were  purchasing  breeding  animals  for  a 
garbage  feeding  establishment  we  would  regard 
it  of  considerable  advantage  to  secure  them  from 
herds  long  accustomed  to  that  kind  of  feed. 

Pigs  must  have  dry  sleeping  quarters  or  they 
will  not  thrive.  Due  to  the  excessive  moisture  in 
garbage,  wet  quarters  are  a  common  and  disas- 
trous cause  of  unthriftiness  among  pigs  that  sub- 
sist on  it.  The  greater  the  run  allowed  the  pigs 
the  easier  it  is  to  keep  them  dry.  When  the  quar- 
ters are  of  necessity  somewhat  crowded,  special 


HOG    CHOLERA   AND    MEAT    INSPECTION  225 

provisions  are  necessary  or  all  parts  of  the  floor 
will  be  damp.  This  difficulty  can  be  obviated  by 
constructing  overlays  consisting  of  floors  of 
matched  material  built  on  two-by-fours  laid  flat. 
These  are  built  up  around  the  edges  so  that  in 
effect  they  are  wide  shallow  boxes  which  contain 
the  litter.  They  should  be  located  as  far  as  pos- 
sible from  the  platform  where  the  garbage  is  fed. 
What  we  have  said  in  preceding  chapters  in 
regard  to  maintaining  herds  immune  to  hog  chol- 
era applies  as  well  to  those  that  subsist  on  gar- 
bage. Young  garbage-fed  pigs  are  relatively 
somewhat  slow  in  getting  started,  hence  they  re- 
quire a  little  extra  care  such  as  we  have  already 
outlined.  In  the  absence  of  this  care  they  are  in 
more  or  less  danger  of  falling  victims  to  various 
influences  that  retard  growth,  or  to  ill  effects  fol- 
lowing simultaneous  treatment  administered  at  a 
time  when  they  are  not  in  the  best  condition  to 
withstand  it. 

Garbage  Feeding  and  Sanitary  Considerations 

We  have  already  described  the  cycle  which 
enables  the  practice  of  garbage  feeding  to  aid  in 
perpetuating  hog  cholera.  The  ways  in  which  this 
cycle  can  be  assailed  remain  to  be  considered. 
Our  attacks  should  include  efforts  to  prevent  ship- 
ment from  cholera  infected  herds,  gradual  revi- 
sion of  our  meat  inspection  regulations  with  a 


226  HOG    CHOLERA 

view  to  reducing  the  number  of  virus  containing 
carcasses  that  are  placed  on  the  market,  measures 
to  license  and  control  establishments  where  gar- 
bage is  fed,  and  educational  activities  designed  to 
acquaint  breeders  with  the  risks  they  assume 
when  they  feed  even  a  limited  quantity  of  garbage. 
Measures  to  prevent  shipment  from  cholera- 
infected  herds  may  take  two  forms:  first,  the  al- 
ternative— prompt  serum  treatment — should  be 
made  available  to  every  breeder,  and  practicing 
veterinarians  will  do  well  to  school  themselves  in 
handling  hog  cholera  on  the  farm,  so  that  the  folly 
of  marketing  infected  hogs  will  be  obvious  to  the 
breeder;  second,  some  form  of  penalty  should  be 
attached  to  the  practice.  It  is  obviously  impos- 
sible to  reach  all  offenders  but  the  more  flagrant 
ones  could  easily  be  detected,  and  the  effect  would 
be  wholesome.  When  a  shipment  of  swine  arrives 
at  the  yards  containing  a  considerable  number  of 
dead  hogs  and  many  others  obviously  infected 
with  cholera,  the  chances  are  that  most  of  the 
animals  in  it  will  produce  carcasses  which  contain 
the  virus.  If  it  could  be  made  compulsory  to 
market  such  carcasses  only  in  the  form  of  safe 
but  less  valuable  cooked  products,  and  if  the  hogs 
in  such  a  shipment  were  so  tagged  and  identified 
that  the  shipper  himself  had  to  accept  the  conse- 
quent loss,  there  would  be  fewer  cholera  infected 


HOG   CHOLERA  AND   MEAT   INSPECTION  227 

herds  marketed,  and  a  higher  price  for  sound  ones 
would  prevail. 

Ante-mortem  inspection  could  at  least  be  made 
to  incriminate  an  entire  shipment  containing  hogs 
obviously  infected  with  cholera  to  the  extent  of 
requiring  a  more  severe  interpretation  of  lesions 
in  individuals  contained  in  it.  While  it  is  true 
that  petechiae  in  the  kidneys  and  peripheral  hem- 
orrhages in  the  lymph  glands,  for  instance,  may 
be  due  to  causes  other  than  cholera,  it  is  likewise 
true  that  in  shipments  such  as  we  have  described 
these  lesions  are,  with  negligible  exceptions,  con- 
clusive evidence  of  the  disease. 

License  and  control  of  garbage  feeding  estab- 
lishments have  much  to  recommend  them.  Sur- 
rounding the  average  city,  under  present  condi- 
tions, are  numerous  small  herds  in  which  garbage 
is  being  fed,  and  in  each  one  lurks  the  danger  of 
an  outbreak  of  hog  cholera.  If  a  licensing  system 
were  in  operation,  instead  of  having  many  un- 
known sources  of  infection  without  any  control 
whatever,  we  would  have  a  limited  number  of 
known  sources,  in  which  methods  could  be  so  regu- 
lated as  to  minimize  danger  due  to  spread  of  the 
infection.  It  would  be  possible  to  require  immu- 
nization of  all  hogs  fed  on  garbage — an  advantage 
rather  than  a  burden  to  the  individual  feeder — 
and  it  would  likewise  be  possible  to  govern  the 


228  HOG   CHOLERA 

location  of  garbage  feeding  establishments,  and 
to  require  adequate  equipment  for  their  operation. 

Regulations  in  Canada  require  that  all  men  who 
plan  to  feed  garbage  shall  first  secure  licenses, 
and  the  plan  seems  to  be  working  well;  princi- 
pally, we  believe,  because  the  sources  of  danger 
are  limited  in  number  and  known.  Cooking  the 
garbage  is  required,  but  this,  in  our  experience, 
is  a  measure  of  doubtful  value.  There  is  no  doubt 
that  a  boiling  temperature  will  kill  the  virus,  but 
there  is  doubt  that  such  a  temperature  will  ac- 
tually be  applied  to  all  garbage  fed  in  any  estab- 
lishment. We  have  frequently  seen  neglect  of  this 
kind  end  in  disaster.  In  one  instance  we  were 
called  to  handle  an  outbreak  of  hog  cholera  at  a 
large  sanitarium  where  provision  had  even  been 
made  for  cooking  all  garbage  under  pressure.  An 
unguarded  interval  during  which  the  apparatus 
was  temporarily  out  of  order  was  responsible  for 
this  outbreak.  Immunizing  the  herd  is  usually 
far  safer  than  cooking  the  garbage  on  which  it  is 
fed,  and  it  has  the  additional  advantage  of  pro- 
tecting against  all  sources  of  infection. 

Despite  the  need  for  various  measures  to  pro- 
tect the  swine  breeder's  herd,  the  fact  remains 
that  the  measures  which  he  himself  can  apply  will 
be  most  effective.  He  can  exclude  all  pork  trim- 
mings from  the  kitchen  refuse  which  he  feeds,  he 
can  discontinue  feeding  garbage,  or  he  can  in  co- 


HOG   CHOLERA   AND    MEAT   INSPECTION  229 

operation  with  his  veterinarian  keep  his  herd  im- 
munized. Either  measure  faithfully  carried  out 
will  protect  his  herd  from  cholera  infection  di- 
rectly due  to  garbage  feeding. 


CHAPTER  XI 

CONTROL   AND    EEADICATION    OF    HOG.   CHOLERA 

CONTROL  of  an  infectious  disease  means  that 
rather  definite  limits  have  been  placed  on  its 
spread.  Eradication,  as  applied  to  a  particular 
area,  implies  that  all  the  virus  which  causes  the 
disease  has  been  killed,  and  that  the  malady  can 
no  longer  exist  unless  it  is  introduced  from  with- 
out. Naturally,  in  a  country  in  which  an  acute 
and  fatal  infectious  disease  such  as  hog  cholera 
is  widely  disseminated  control  is  the  first  con- 
sideration. But  eradication  is  the  distant  goal, 
and  while  our  progress  toward  this  goal  must  at 
times  yield  to  expediency,  there  must  be  no  per- 
manent or  long  surrender  to  methods  that  con- 
tribute nothing  toward  the  ultimate  purpose. 

Long  acceptance  of  losses  due  to  hog  cholera 
has  given  us  a  fatalistic  attitude  toward  the  dis- 
ease. Like  the  poor,  it  is  always  with  us  and  we 
habitually  expect  and  tolerate  it  as  we  expect  and 
tolerate  inclemencies  of  weather  or  the  infirmi- 
ties of  old  age.  If  a  foreign  infectious  swine  dis- 
ease, equally  destructive  and  equally  well  under- 
stood, were  to  appear  in  this  country,  even  though 

230 


CONTROL    AND    ERADICATION    OF    HOG    CHOLERA  231 

it  were  to  gain  a  firm  foothold,  those  whose  inter- 
ests were  threatened  would  demand  its  eradica- 
tion and  the  veterinary  profession  in  cooperation 
with  many  breeders — and  in  spite  of  the  violent 
opposition  of  a  few — would  eradicate  it. 

The  first  prerequisite,  then,  is  a  change  on  the 
part  of  veterinarians,  breeders  and  the  public 
from  a  passive  to  an  active  attitude  toward  hog 
cholera.  In  expressing  this  view  we  must  not  be 
understood  as  declaring  our  faith  in  a  short  and 
intensified  campaign  against  the  disease,  for  the 
methods  that  finally  succeed  will  involve  details 
which  must  grow  out  of  a  continual  process  of 
trial  and  adjustment ;  but  the  start  must  be  made, 
the  goal  must  be  kept  clearly  in  view,  and  con- 
stant, active  and  unyielding  pressure  must  be 
brought  to  bear  on  the  most  obvious  practices  that 
serve  to  perpetuate  the  disease. 

During  the  last  four  decades  hog  cholera  has 
caused  in  this  country  annual  losses  ranging  be- 
tween $13,000,000  and  $200,000,000,  killing  annu- 
ally an  average  of  66  out  of  every  1,000  hogs. 
About  once  in  each  decade  the  disease  becomes 
greatly  intensified  and  in  1887,  1897  and  1914, 
respectively,  the  number  of  hogs  killed  by  it  rose 
above  10  per  cent  of  the  country's  entire  swine 
population.  These  are  staggering  losses,  and 
when  one  reflects  that  they  will  continue  indefi- 
nitely unless  intelligent,  organized  efforts  are 


232  HOG    CHOLEKA 

made  to  check  them  the  advantages  of  such  efforts 
become  self-evident. 

It  is  not  impossible  to  eradicate  hog  cholera. 
The  task  presents  no  such  difficulties  as  are  en- 
countered in  the  eradication  of  bovine  tuberculo- 
sis, for  instance.  Hog  cholera  does  not  exist  long 
unknown  to  the  owner  of  the  herd  it  infects;  indi- 
viduals apparently  well  do  not  regularly  live  year 
after  year  disseminating  the  virus ;  deaths  due  to 
it  are  rapid  and  certain  and  the  resulting  losses 
are  obvious;  it  is  a  foe  that  strikes  in  the  open. 
The  disease  can  be  stamped  out  quickly  in  any 
herd,  and  there  is  an  immunizing  agent  so  effec- 
tive that  prompt  reporting  is  the  breeder's  surest 
way  to  avoid  loss.  When  we  reflect  on  the  sig- 
nificance of  these  facts  we  may  well  be  led  to 
wonder  why  the  disease  does  not  disappear.  The 
truth  is  that  it  does  tend  to  do  so,  for  undoubtedly 
there  are  to-day  many  counties  free  from  the  dis- 
ease that  have  suffered  severely  from  it  in  past 
years,  and  that  will  suffer  again  when  the  virus 
once  more  is  introduced  from  without. 

When  once  the  virus  finds  its  way  into  a  locality 
the  methods  by  which  it  may  spread  from  herd  to 
herd  are  innumerable  but  it  is  time  that  we  direct 
our  attention  to  the  sources  of  the  original  infec- 
tions. We  dissipate  our  energies  in  trying  to  con- 
trol outbreaks  of  huge  proportions  instead  of 
concentrating  them  on  the  prevention  of  primary 


CONTROL  AND  ERADICATION  OF  HOG  CHOLERA     233 

infections.  The  three  most  important  methods  by 
which  hog  cholera  travels  from  locality  to  locality 
are: 

1.  Marketing  from  infected  herds.     The  hogs 
thus  shipped  are  a  menace  to  others  as  they  are 
taken  to  market,  they  keep  stock  cars  and  stock- 
yards constantly  infected,  they  are  sometimes  sold 
from  the  yards  as  feeders,  and  their  carcasses  are 
regularly  placed  on  the  market  in  large  numbers 
where  they  serve  to  infect  many  new  localities 
through  the  medium  of  garbage  feeding. 

2.  The     transportation     from     public     stock- 
yards   of    susceptible    feeder    hogs,    and    those 
which    receive    simultaneous    treatment    imme- 
diately   prior    to    shipping.      When    susceptible 
feeders  are  placed  in  public  stockyards  they  often 
become  infected,  and  though  they  leave  the  yards 
apparently   in   good   health    they    soon    develop 
cholera  and  the  farms  which  receive  them  become 
new  centers  of  infection.  Feeder  hogs  that  receive 
simultaneous  treatment  and  which  are  at  once 
shipped  to  distant  points,  frequently  ' ' break "  as 
a  result,  and  thus  introduce  hog  cholera  into  new 
territory. 

3.  Wide  and  indiscriminate  use  of  hog  cholera 
virus    in   immunizing,    especially    by   untrained 
men.    " Vaccination  cholera"  is  still  too  common 
in  farm  herds,  despite  the  fact  that  experienced 
men  know  how  to  avoid  most  of  it. 


234  HOG    CHOLEEA 

These  three  practices  have  essentially  the  same 
relation  to  hog  cholera  eradication  that  the  feed- 
ing of  uncooked  creamery  products  has  to  the 
eradication  of  bovine  tuberculosis.  They  furnish 
obvious  and  wide-open  routes  for  dissemination 
of  the  virus.  Are  they  really  necessary  evils? 
Are  there  no  possible  ways  to  avoid  them?  Let 
us  examine  the  three  practices  more  in  detail. 

Marketing  from  infected  herds.  We  have  al- 
ready shown  that  marketing  from  infected  herds 
is  a  common  practice,  that  it  serves  to  spread  hog 
cholera  virus  as  the  animals  are  driven  to  market 
and  when  trimmings  from  their  carcasses  later 
find  their  way  into  garbage  that  is  fed  to  suscep- 
tible hogs.  We  have  also  drawn  attention  to  the 
fact  that  feeders  selected  from  these  herds  and 
shipped  to  distant  points  cause  many  new  out- 
breaks of  hog  cholera.  For  our  present  purpose 
it  remains  to  review  briefly  means  by  which  this 
endless  chain  of  infection  can  be  severed. 

The  first  object  should  be  to  keep  cholera  in- 
fected herds  at  home.  Good  local  veterinary  serv- 
ice will  do  much  in  this  direction  for  it  is  the  ill- 
advised  breeder  who  ships  his  infected  hogs  to 
market.  On  the  part  of  the  meat  inspection  serv- 
ice, rigid  interpretations  of  lesions  in  all  indi- 
viduals that  come  from  lots  obviously  infected 
with  hog  cholera  at  the  time  they  reach  the  yards 


CONTROL   AND    ERADICATION    OF    HOG    CHOLERA  235 

will  serve  to  discourage  shipping  from  infected 
herds,  provided  a  tagging  system  is  adopted  which 
will  place  the  losses  due  to  condemnations  where 
they  belong — on  the  man  who  ships  the  hogs. 

The  second  object  should  be  to  prevent  the  sale 
of  carcasses  of  infected  hogs  that  reach  market 
despite  efforts  to  keep  them  away.  In  other 
words,  carcasses  that  obviously  are  carriers  of 
hog  cholera  virus  should  not  be  sold  except  in  the 
form  of  cooked  products,  for  hog  cholera  will  be 
with  us  as  long  as  the  practice  continues.  We 
have  already  mentioned  the  present  deficiency  of 
the  federal  meat  inspection  regulations  as  they 
apply  to  this  particular  point.  Whether  this  de- 
ficiency is  due  to  lack  of  authority  or  to  failure  to 
use  authority  already  granted,  the  effect  is  the 
same — many  carcasses  that  show  lesions  usually 
considered  characteristic  of  hog  cholera  are  still 
allowed  to  pass  inspection. 

It  is  deceptive  to  assert,  as  the  regulations  do, 
that  these  lesions  are  sometimes  due  to  causes 
other  than  hog  cholera.  Granting,  as  we  freely 
do,  that  this  is  true  we  still  maintain  that  it  is 
exceptional  to  such  an  extent  that  it  should  re- 
ceive scant  consideration  in  the  judgment  of  car- 
casses that  come  from  lots  which  contain  hogs 
suffering  with  cholera  when  they  reach  the  yards. 
Hogs  that  come  from  infected  herds  and  that  show 


236  HOG    CHOLERA 

even  slight  lesions  suggestive  of  cholera  will  yield 
carcasses  that  contain  virus,  almost  without  ex- 
ception. 

The  third  object  sought  should  be  that  of  neu- 
tralizing the  effects  of  virus-carrying  carcasses 
that  pass  inspection.  To  this  end  it  should  be 
made  known  among  swine  raisers  that  danger  al- 
ways lurks  in  the  practice  of  feeding  even  small 
quantities  of  garbage  that  contain  pork  trim- 
mings. A  system  of  licensing  garbage-feeding 
such  as  the  one  that  now  exists  in  Canada,  is  also 
worthy  of  consideration. 

Transportation  and  sale  of  susceptible  feeder 
hogs  and  those  which  receive  simultaneous  treat- 
ment just  before  shipping.  Most  public  stock- 
yards are  contaminated  with  hog  cholera  virus, 
and  eventually  it  should  be  so  ordered  that  when 
susceptible  hogs  enter,  it  shall  be  for  immediate 
slaughter  only,  and  the  gates  shall  close  behind 
them  forever.  Previously  we  have  drawn  atten- 
tion to  the  fact  that  "  serum  breaks "  are  fre- 
quently a  result  of  giving  hogs  simultaneous  treat- 
ment and  shipping  them  immediately  afterward. 

Though  this  practice  is  probably  the  lesser  evil 
as  compared  to  shipping  susceptible  hogs  from  the 
yards  without  immunization,  the  fact  remains  that 
it  is  still  a  potent  factor  in  the  dissemination  of 
hog  cholera  virus.  Follow-up  treatment  as  a  sub- 
stitute for  simultaneous  treatment  given  immedi- 


CONTROL   AND    ERADICATION    OF    HOG    CHOLERA  237 

ately  before  shipping,  will  do  much  to  minimize 
this  danger,  but  the  ideal  will  be  reached  only 
when  feeder  hogs  are  permanently  immune  to  hog 
cholera  before  they  are  shipped  long  distances. 

It  will  take  time  to  provide  for  an  adequate 
supply  of  immune  feeders  so  that  shipping  suscep- 
tible and  recently-immunized  hogs  from  public 
stockyards  will  not  be  necessary,  but  there  are 
hopeful  indications  that  this  will  be  brought  about. 
Men  experienced  in  the  feed-yard  even  now  are 
eagerly  seeking  means  of  avoiding  the  heavy 
financial  losses  associated  with  "vaccination 
cholera "  immediately  following  simultaneous 
treatment  and  shipping.  Among  such  men  there 
is  an  active  demand  for  immune  feeder  shoats, 
and  efforts  are  being  made,  though  as  yet  on  a 
limited  scale,  to  supply  this  demand.  The  prac- 
tice of  assembling  and  immunizing  feeders,  and 
shipping  them  only  after  the  resulting  reaction 
is  over  is  already  being  adopted  by  some  serum 
companies.  This  is  a  step  in  the  right  direction, 
and  our  belief  is  that  a  promising  field  is  open  to 
others  who  will  make  a  business  of  supplying  the 
trade  with  carefully  selected  cholera  -  immune 
feeder  shoats.  When  the  supply  of  these  animals 
is  equal  to  the  demand  the  practice  of  shipping 
susceptible  and  recently-immunized  feeders  from 
public  stockyards  will  cease. 

Indiscriminate  use  of  hog  cholera  virus  in  im- 


238  HOG   CHOLEBA 

mumzing.  When  the  effectiveness  of  serum-virus 
immunization  was  first  demonstrated  the  demand 
for  these  products  far  exceeded  the  supply,  and 
hasty  preparations  were  made  to  produce  them  in 
enormous  quantities.  Enthusiasm  for  immuniza- 
tion ran  high,  and  it  was  looked  on  as  the  final 
solution  of  the  hog  cholera  problem.  Men  with- 
out previous  experience  with  disease  and  with 
no  fundamental  knowledge  of  the  processes  that 
produce  immunity  were  drafted  into  service  to 
produce  and  use  products  potentially  capable  of 
doing  great  harm.  It  was  the  accepted  belief  that 
all  hogs  should  be  immunized,  that  the  process  of 
immunization  was  a  simple  one  requiring  only  a 
low  grade  of  mechanical  skill,  that  serum  and 
virus  could  be  administered  without  a  suggestion 
of  danger,  and  that  the  hogs  receiving  them  were 
from  the  moment  the  doses  were  administered 
permanently  immune  to  hog  cholera.  It  is  little 
wonder  that  impotent  serum  was  sent  out,  that 
potent  serum  often  fell  into  unskilled  hands,  and 
that  some  of  the  laboratories  that  featured  "  virus 
q.  s.  with  all  serum  orders "  sometimes  sent  out 
quantities  that  were  just  a  little  more  than  suffi- 
cient. 

The  Bureau  of  Animal  Industry  laboratory  in- 
spection service  with  the  aid  of  many  far-sighted 
serum  companies  has  done  much  to  correct  these 
initial  evils.  The  sale  of  impotent  serum  for  use 


CONTROL  AND  ERADICATION  OP  HOG  CHOLERA     239 

with  virus  was  much  more  readily  prevented  than 
were  the  disasters  growing  out  of  the  use  of  good 
serum  by  untrained  or  indifferent  men,  and  to- 
day it  is  to  the  latter  abuse  that  most  outbreaks 
of  hog  cholera  which  originate  from  laboratory 
virus  must  be  attributed. 

The  task  of  reducing  "vaccination  cholera"  to 
a  minimum  must  be  referred  to  a  trained  and 
awakened  veterinary  profession.  There  is  an  in- 
sistent demand  that  vaccination  of  hogs  shall  be 
placed  in  the  hands  of  laymen,  a  policy  which,  if 
adopted  generally,  will  be  disastrous  to  the  swine 
industry.  Yet  this  demand  will  be  heard — and 
heeded — as  long  as  there  is  territory  in  which 
there  are  not  qualified  veterinarians  to  do  the 
work. 

Eeducing  the  problem  of  hog  cholera  control  to 
its  simplest  terms  it  may  be  said  that  in  the  indi- 
vidual animal  the  disease  soon  terminates,  for  the 
virus  will  destroy  or  immunize  its  host  in  a  few 
weeks.  Likewise  in  the  herd  the  same  principle 
applies,  but  if  we  expand  our  unit  to  include 
county,  state  or  nation  the  difficulties  that  present 
themselves  multiply  accordingly.  The  limiting 
factors  in  the  control  of  the  disease  are  lack  of 
thoroughly  trained  men,  lack  of  understanding  on 
the  part  of  the  public,  and  the  expense  involved. 

The  federal  Bureau  of  Animal  Industry  has 


240  HOG    CHOLERA 

demonstrated  that  the  disease  can  be  kept  down  in 
individual  counties,  but  the  expense  involved  was 
so  great  as  to  forbid  use  of  the  plan  on  a  large 
scale.  Area  work  in  the  eradication  of  hog  chol- 
era is,  we  believe,  wrong  in  its  conception  as  long 
as  the  virus  continually  invades  the  selected  terri- 
tory from  without  through  the  three  channels  that 
have  just  been  indicated. 

No  successful  standardized  plan  for  the  control 
of  hog  cholera  has  yet  appeared.  Killing  infected 
and  exposed  animals  and  indemnifying  the  owners 
has  been  tried  in  England  and  Canada  but  results 
have  not  been  such  as  to  recommend  wide  applica- 
tion of  the  plan.  Immunizing  all  hogs  against 
cholera  was  once  enthusiastically  recommended, 
but  we  doubt  if  there  can  be  found  to-day  an  ex- 
perienced man  who  considers  this  method  feasible. 
It  would  involve  the  principle  of  forcing  owners 
to  vaccinate,  the  expense  would  be  prohibitive, 
and  the  trained  men  necessary  to  carry  it  out  do 
not  exist. 

In  our  appraisal  of  the  cooperative  forces 
which  can  be  brought  to  bear  immediately  in  hog 
cholera  eradication  we  must  include  the  swine 
breeder,  the  practicing  veterinarian,  the  official 
veterinarian  and  the  serum  producer. 

The  breeder  should  be  acquainted  with  the 
methods  by  which  hog  cholera  is  spread  so  as  to 
be  able  to  protect  his  herd  against  extraneous 


CONTROL   AND    ERADICATION    OF    HOG    CHOLERA  241 

infection.  He  should,  with  the  advice  of  his 
veterinarian  determine  whether  his  herd  is  to  be 
maintained  immune  to  hog  cholera,  or  whether  it 
is  to  remain  susceptible  and  be  kept  under  obser- 
vation. In  case  the  former  plan  is  adopted  the 
practice  of  immunizing  should  not  be  allowed  to 
lag,  and  in  case  the  latter  seems  advisable  he 
should  report  promptly  any  infectious  disease 
that  appears. 

The  practicing  veterinarian's  part  consists  in 
snuffing  out  the  outbreaks  as  fast  as  they  appear, 
in  aiding  owners  to  clean  up  their  herds  so  that 
they  will  not  serve  to  infect  others  in  the  vicinity, 
in  doing  the  vaccinating  incident  to  maintaining 
immune  herds,  and  in  advising  his  clients  relative 
to  methods  by  which  their  herds  can  best  be  pro- 
tected. Only  when  the  need  for  police  power  ap- 
pears does  the  province  of  the  practitioner  ter- 
minate and  that  of  the  official  veterinarian  begin. 

The  official  veterinarian's  primary  duty  is  to 
bring  pressure  to  bear  on  the  three  principal 
practices  that  serve  to  spread  hog  cholera  from 
locality  to  locality.  By  placing  restrictions  on  the 
sale  of  hogs  from  infected  herds  and  from  public 
stockyards ;  by  a  far  more  severe  interpretation  of 
hog-cholera-like  lesions  in  the  administration  of 
meat  inspection  regulations ;  by  restricting  the  use 
of  virus  so  that  only  trained  men  may  handle 
it;  and  by  continued  supervision  of  commercial 


242  HOG    CHOLERA 

serum  laboratories  the  official  veterinarian  can 
play  an  indispensable  part  in  the  fight  against  hog 
cholera. 

The  serum  producer's  part  is  to  supply  suffi- 
cient potent  serum  to  immunize  all  hogs  that  ac- 
tually require  immunization.  Despite  notable  ex- 
ceptions it  must  be  said  that  on  the  whole  the  part 
has  been  played  well,  and  when  breeders,  prac- 
ticing veterinarians  and  official  veterinarians,  as 
classes,  meet  their  obligations  as  well  as  the  serum 
producer  is  meeting  his,  there  will  be  far  less  hog 
cholera  in  the  country. 

Volumes  could  be  written  on  the  eradication  of 
hog  cholera  if  we  were  to  follow  the  various  rami- 
fications into  which  details  of  the  problem  lead  us. 
There  are  the  questions  of  uniform  regulations 
for  interstate  shipment  of  swine ;  of  separate  reg- 
ulations for  crated  swine;  of  rules  governing  the 
exhibition  of  hogs  at  fairs ;  and  of  funds  to  admin- 
ister laws  and  regulations  that  are  already  pro- 
vided. These  and  many  other  supplementary 
problems  appear  but  consideration  of  them  here 
would  only  cloud  the  more  important  issues. 

The  points  we  emphasize  in  closing  are  that  at 
the  present  time  the  obstacles  presented  in  the 
eradication  of  hog  cholera  rest  not  so  much  in 
lack  of  machinery  to  do  the  work  as  in  the  manner 
in  which  the  existing  machinery  functions;  that 
three  well-known  wide-open  routes  for  the  inter- 


CONTROL   AND    ERADICATION    OF    HOG    CHOLERA  243 

sectional  spread  of  hog  cholera  virus  still  exist 
and  that  they  must  be  closed  as  the  first  step  to- 
ward substantial  progress  in  eradicating  the  dis- 
ease. Only  when  this  is  accomplished  can  we 
correctly  appraise  the  lesser  task  that  will  yet 
remain.  At  present  the  country's  attitude  toward 
hog  cholera  eradication  may  be  likened  to  that  of 
a  farmer  who  each  year  sows  weed  seeds  with  his 
grain,  and  then  labors  diligently  to  eradicate  the 
weeds  that  spring  up.  Let  us  stop  sowing  the  seed. 

REFERENCES 

The  following  references  have  been  selected  from  the 
numerous  publications  on  hog  cholera  because  most  of 
them  are  available  to  the  American  veterinarian,  and 
because,  as  a  group,  they  cover  the  subject  in  a  fairly 
complete  and  satisfactory  manner.  No  attempt  has  been 
made  to  include  a  complete  bibliography. 

BIRCH,  R.  R.,  "Hog  Cholera  and  Its  Prevention,"  Cor- 
nell Veterinarian,  Hog  Cholera  Number,  May,  1916. 

BIRCH,  R.  R.,  "Garbage  Feeding  and  the  Care  of  Gar- 
bage-fed Swine,"  Cornell  Veterinarian,  January, 
1918,  p.  26. 

BIRCH,  R.  R.,  "Hog  Cholera  Transmission  Through  In- 
fected Pork,"  Journal  of  the  Am.  Vet.  Med.  Assn., 
June,  1917,  p.  303. 

BIRCH,  R.  R.,  "Researches  in  Regard  to  Immunizing 
Young  Pigs, ' '  Report  of  the  New  York  State  Veter- 
inary College  at  Cornell  University,  1918-1919, 
p.  73. 

CAHILL,  E.  A.,  "Hog  Cholera  Control  in  the  East," 
Journal  of  the  Am.  Vet.  Med.  Assn.,  January,  1919, 
p.  314. 


244  HOG    CHOLERA 

CAHILL,  E.  A.,  "Relative  Potency  of  Tail-bled  and 
Carotid-bled  Anti-hog-cholera  Serum,"  Journal  of 
the  Am.  Vet.  Med.  Assn.,  November,  1919,  p.  177. 

CONNOWAY,  J.  W.,  "Hog  Cholera  and  Immature  Corn," 
Bulletin  No.  74,  University  of  Missouri  College  of 
Agriculture. 

DE  SCHWEINITZ  AND  DORSET,  "A  Form  of  Hog  Cholera 
not  Caused  by  the  Hog  Cholera  Bacillus, ' '  Circular 
No.  41,  U.  S.  Bureau  of  Animal  Industry. 

DIMOCK,  W.  W.,  "Differential  Diagnosis  of  Diseases  of 
the  Pig,"  Journal  of  the  Am.  Vet.  Med.  Assn.,  Janu- 
ary, 1919,  p.  321. 

DORSET,  BOLTON,  MCBRYDE,  "The  Etiology  of  Hog 
Cholera,"  Bulletin  No.  72,  U.  S.  Bureau  of  Animal 
Industry. 

DORSET,  McBRYDE,  NILES,  "Further  Experiments  Con- 
cerning the  Production  of  Immunity  from  Hog 
Cholera,"  Bulletin  No.  102,  U.  S.  Bureau  of  Animal 
Industry. 

DORSET,  M.,  AND  HOUCK,  U.  G.,  "Hog  Cholera,"  Farm- 
ers' Bulletin  No.  834,  U.  S.  Department  of  Agricul- 
ture. 

DORSET,  M.,  MCBRYDE,  C.  N.,  NILES,  W.  B.,  RIETZ,  J.  H., 
"Studies  on  Hyperimmunization  against  Hog  Chol- 
era," Journal  of  the  Am.  Vet.  Med.  Assn.,  June, 
1919,  p.  259. 

EICHHORN,  A.,  "Present  Status  of  Hog  Cholera  Con- 
trol, ' '  Journal  of  the  Am.  Vet.  Med.  Assn.,  October, 
1919,  p.  51. 

FRINK,  "W.  E.,  "The  Control  of  Hog  Cholera,"  Cornell 
Veterinarian,  October,  1920,  p.  244. 

HOSKINS,  H.  PRESTON,  "Notes  on  the  Occurrence  of 
Petechial  Hemorrhages  in  the  Larynx  and  Kidneys 
in  Hog  Cholera,"  Journal  of  the  Am.  Vet.  Med. 
Assn.,  July,  1916,  p.  478. 

HOSKINS,  H.  PRESTON,  "Observations  on  2800  Pigs  In- 
oculated with  Hog  Cholera  Virus,"  Journal  of  the 
Am.  Vet.  Med.  As<sn.,  September,  1915,  p.  817. 


CONTROL   AND    ERADICATION    OF    HOG    CHOLERA  245 

HOUCK,  U.  G.,  "Progress  in  Hog  Cholera  Control," 
Journal  of  the  Am.  Vet.  Med.  Assn.,  January,  1920, 
p.  359. 

KEBNKAMP,  H.  C.  H.,  "The  Longevity  of  the  Virus  of 
Hog  Cholera,"  Cornell  Veterinarian,  January,  1920, 

P.I. 

KERNKAMP,  H.  C.  H.,  "Results  of  Experiments  to  Note 
the  Effects  of  Freezing  on  Anti-hog-Cholera  Se- 
rum," Cornell  Veterinarian,  January,  1918,  p.  7. 

KING,  W.  E.,  AND  HOFFMAN,  G.  L.,  "Spirochaeta  Suis: 
Its  Significance  as  a  Pathogenic  Organism,  ' '  Journal 
of  Infectious  Diseases,  Vol.  13,  p.  463. 

KING,  W.  E.,  BAESLACH,  F.  W.,  HOFFMAN,  G.  L.,  "Stud- 
ies on  the  Virus  of  Hog  Cholera, ' '  Am.  Vet.  Review, 
Vol.  44,  p.  555. 

KINSLEY,  A.  T.,  Surine  Practice  (Am.  Veterinary  Pub- 
lishing Co.,  Chicago). 

LYNCH,  CHAS.  F.,  Diseases  of  Swine  (W.  B.  Saunders 
Co.,  Philadelphia). 

MOORE,  V.  A.,  DIMOCK,  W.  W.,  HARING,  C.  M.,  GILLI- 
LAND,  S.  H.,  KINSLEY,  A.  T.,  "Report  of  the  Com- 
mittee on  Diseases,"  Journal  of  the  Am.  Vet.  Med. 
Assn.,  November,  1915,  p.  207. 

MEYER,  "The  Filterable  Viruses,"  Am.  Vet.  Review, 
Vol.  46,  No.  2,  p.  132. 

NILES,  W.  B.,  "Field  Tests  with  Serum  for  the  Preven- 
tion of  Hog  Cholera,"  Report  of  the  U.  S.  Bureau 
of  Animal  Industry,  1908. 

NILES,  W.  B.,  RIETZ,  J.  H.,  "Immunity  of  Young  Pigs," 
Journal  or  the  Am.  Vet.  Med.  Assn.,  May,  1920, 
p.  176. 

PALMER,  C.  B.,  "The  Hog  in  Relation  to  Municipal  Gar- 
bage," Journal  of  the  Am.  Vet.  Med.  Assn.,  1918, 
p.  227. 

PICKENS,  E.  M.,  WELSH,  M.  F.,  POLEMA,  L.  J.,  "The 
Susceptibility  of  Young  Pigs  to  Cholera, ' '  Journal 
of  the  Am.  Vet.  Med.  Assn.,  October,  1921,  p.  22. 

RECORDS,  EDWARD,  ' '  Purification  and  Concentration  of 
Hog  Cholera  Serum,"  Journal  of  the  Am.  Vet. 
Med.  Assn.,  December,  1919,  p.  291. 


246  HOG   CHOLERA 

STANGE,  C.  H.,  "Hog  Cholera  Control,"  Jmirnal  of  the 
Am.  Vet  Med.  Asfsn.,  November,  1915,  p.  156. 

TORRANCE,  FREDERICK,  ' '  Garbage  Feeding  in  Relation  to 
the  Control  of  Hog  Cholera,"  Journal  of  the  Am. 
Vet.  Med.  Assn.,  October,  1921,  p.  22. 


APPENDIX 

B.  A.  I.  Order  265.  Issued  September  12,  1919. 

UNITED  STATES  DEPARTMENT  OF 
AGRICULTURE 

Bureau  of  Animal  Industry 
JOHN  R.  MOHLER,  Chief  of  Bureau 

Regulations  Governing  the  Preparation,  Sale,  Barter, 
Exchange,  Shipment,  and  Importation  of  Viruses, 
Serums,  Toxins,  and  Analogous  Products  Intended  for 
Use  in  the  Treatment  of  Domestic  Animals. 

Effective  on  and  after  September  1,  1919 
CONTENTS 

Page. 

Regulation  1.  Definitions  248 

Regulation  2.  Licenses  and  inspections  251 

Regulation  3.  Permits    254 

Regulation  4.  Suspension  or  revocation  of  licenses 

and  permits   256 

Regulation  5.  Notice  to  licensees  and  permittees . .  257 

Regulation  6.  Assignment  of  bureau  employees. . .  257 

Regulation  7.  Facilities  for  inspection 258 

Regulation  8.  Sanitation   258 

Regulation  9.  Sterilization    261 

Regulation  10.  Storage    262 

Regulation  11.  Records    262 

Regulation  12.  Labels   263 

Regulation  13.  Collecting  samples    265 

Regulation  14.  Testing   266 

Regulation  15.  Retesting 266 

247 


248  HOG   CHOLEKA 

Page. 

Regulation  16.  Reports    266 

Regulation  17.  Animals 267 

Regulation  18.  Hog-cholera  virus   274 

Regulation  19.  Anti-hog-cholera  serum   282 

Regulation  20.  Bacterins,  vaccines,  toxins,  etc. . . .  295 
Regulation  21.  Admission  of  viruses,  serums,  tox- 
ins, and  analogous  products 296 

The  virus-serum-toxin  law 296 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

OFFICE  OF  THE  SECRETARY, 
Washington,  D.  C.,  August  1,  1919. 

Under  authority  of  the  act  of  Congress  approved 
March  4,  1913,  entitled  "An  act  making  appropriations 
for  the  Department  of  Agriculture  for  the  fiscal  year 
ending  June  30,  1914"  (37  Stat.,  832),  the  following 
regulations  are  hereby  issued  for  the  purpose  of  en- 
forcing the  provisions  of  said  act  governing  the  prepara- 
tion, sale,  barter,  exchange,  shipment,  and  importation 
of  viruses,  serums,  toxins,  and  analogous  products  in- 
tended for  use  in  the  treatment  of  domestic  animals. 
These  regulations,  which  for  the  purpose  of  identification 
are  designated  as  B.  A.  I.  Order  265,  shall  become  and 
be  effective  on  and  after  September  1,  1919,  except  that 
stocks  of  approved  labels  on  hand  may  be  used  until 
December  31,  1920. 

D.  F.  HOUSTON, 
Secretary  of  Agriculture. 

REGULATION    1. — DEFINITIONS 

SECTION  1.  Paragraph  1.  For  the  purpose  of  these 
regulations  the  following  words,  phrases,  names,  and 
terms  shall  be  construed  respectively  to  mean: 

Paragraph  2.  The  virus-serum-toxin  act  of  1913  :  "An 
act  making  appropriations  for  the  Department  of  Agri- 


APPEOT)IX  249 

culture  for  the  fiscal  year  ending  June  30,  1914,"  ap- 
proved March  4,  1913  (37  Stat.,  832). 

Paragraph  3.  Viruses,  serums,  toxins,  and  analogous 
products  or  veterinary  biologies:  All  viruses,  serums, 
toxins,  and  analogous  products,  such  as  antitoxins,  vac- 
cines, tuberculins,  malleins,  microorganisms,  killed  micro- 
organisms, and  products  of  microorganisms  which  are 
intended  for  use  in  the  treatment  of  domestic  ani- 
mals. 

Paragraph  4.  The  department :  The  United  States  De- 
partment of  Agriculture. 

Paragraph  5.  The  bureau :  The  Bureau  of  Animal  In- 
dustry of  the  United  States  Department  of  Agriculture. 

Paragraph  6.  Bureau  employee:  Any  officer,  agent, 
or  other  individual  employed  in  the  Bureau  of  Animal 
Industry,  who  is  authorized  by  the  chief  of  the  bureau  to 
do  any  work  or  perform  any  duty  in  connection  with  the 
execution  of  the  provisions  of  the  virus-serum-toxin  act 
of  1913. 

Paragraph  7.  Veterinary  inspector :  A  veterinary  in- 
spector of  the  Bureau  of  Animal  Industry. 

Paragraph  8.  Licensed  establishment:  Any  establish- 
ment owned  or  operated  by  a  person,  firm,  or  corporation 
holding  an  unexpired,  unsuspended,  and  unrevoked  li- 
cense issued  by  the  Secretary  of  Agriculture  for  the 
preparation  of  any  virus,  serum,  toxin,  or  analogous 
product. 

Paragraph  9,  Official  station :  One  or  more  licensed 
establishments  included  under  a  single  supervision. 

Paragraph  10.  Inspector  in  charge :  An  inspector  as- 
signed to  supervise  and  perform  official  work  at  an  offi- 
cial station  and  who  reports  directly  to  the  chief  of  the 
bureau. 

Paragraph  11.  Person :  Natural  persons,  individuals, 
firms,  partnerships,  corporations,  companies,  societies, 
and  associations  and  every  agent,  officer,  or  employee 


250  HOG    CHOLEKA 

thereof.  This  term  shall  import  both  the  plural  and 
the  singular,  as  the  case  may  be. 

Paragraph  12.  Hog-cholera  virus:  The  clear  serum, 
plasma,  or  denbrinated  blood,  derived  from  hogs  sick  of 
hog  cholera  and  free  from  other  communicable  disease 
or  diseases. 

Paragraph  13.  Hyperimmunizing  virus :  Hog-cholera 
virus  prepared  for  hyperimmunizing  hogs  which  are  im- 
mune to  the  disease  hog  cholera. 

Paragraph  14.  Simultaneous  virus :  Hog-cholera  virus 
prepared  for  inoculating  hogs  which  are  to  be  injected 
simultaneously  with  anti-hog-cholera  serum  for  the  im- 
munization of  those  animals  against  the  disease  hog 
cholera. 

Paragraph  15.  Anti-hog-cholera  serum:  The  clear 
serum,  plasma,  or  defibrirrated  blood,  or  derivatives  there- 
of, containing  the  protective  principles  derived  from  im- 
mune hogs  which  have  been  hyper-immunized  by  an  in- 
travenous injection  of  at  least  5  cubic  centimeters,  per 
pound  body  weight,  of  the  virus  of  hog  cholera. 

Paragraph  16.  Immediate  or  true  container:  The 
unit,  bottle,  vial,  ampule,  tube,  or  other  receptacle  or  con- 
tainer in  which  any  virus,  serum,  toxin,  or  analogous 
product  is  customarily  sold  or  distributed. 

Paragraph  17.  Serial  number :  The  number  given  each 
batch  of  virus,  serum,  toxin,  or  analogous  product  to 
identify  the  said  virus,  serum,  toxin,  or  analogous  prod- 
uct with  the  records  of  preparation  thereof. 

Paragraph  18.  Return  date:  The  date  placed  upon 
trade  labels  affixed  to  or  used  in  connection  with  imme- 
diate or  true  containers  of  viruses,  serums,  toxins,  and 
analogous  products  by  producers  to  indicate  the  limit 
of  time  during  which  the  said  products  may  be  expected 
to  retain  their  full  strength  or  potency. 

Paragraph  19.  U.  S.  Released:  That  veterinary  bi- 
ologies so  marked  have  been  prepared  and  tested  in  ac- 


APPENDIX  251 

cordance  with  the  provisions  of  these  regulations  and 
that  when  thus  prepared,  tested,  and  marked,  they  were 
not  worthless,  contaminated,  dangerous,  or  harmful. 

REGULATION   2. — LICENSES   AND   INSPECTIONS 

SECTION  1.  Every  establishment  in  the  United  States 
at  which  any  virus,  serum,  toxin,  or  analogous  product 
is  prepared  for  sale,  barter,  or  exchange  in  the  District 
of  Columbia  or  in  any  Territory  of  or  place  under  the 
jurisdiction  of  the  United  States,  or  for  shipment  or  de- 
livery for  shipment  from  any  State  or  Territory  or  the 
District  of  Columbia  to  any  other  State  or  Territory  or 
the  District  of  Columbia,  shall  hold  an  unexpired,  unsus- 
pended,  and  unrevoked  license,  issued  by  the  Secretary 
of  Agriculture,  and  shall  have  inspection  under  these 
regulations. 

SECTION  2.  All  viruses,  serums,  toxins,  and  analogous 
products  produced  at  licensed  establishments  shall  be 
prepared,  handled,  stored,  marked,  received  for  trans- 
portation, and  transported  as  required  by  these  regula- 
tions. 

SECTION  3.  Paragraph  1.  The  proprietor  or  operator 
of  each  establishment  of  the  kind  specified  in  section  1 
of  this  regulation  shall  make  application  in  writing  to 
the  Secretary  of  Agriculture  for  a  license.  When  one 
proprietor  conducts  more  than  one  establishment,  a  sep- 
arate application  shall  be  made  for  a  license  for  each 
establishment.  Blank  forms  of  application  will  be  fur- 
nished upon  request  addressed  to  the  Bureau  of  Animal 
Industry,  Washington,  D.  C. 

Paragraph  2.  Triplicate  copies  of  plans,  properly 
drawn  to  scale,  and  of  specifications,  including  plumbing 
and  drainage  of  establishments,  together  with  triplicate 
copies  of  all  labels  and  advertising  matter  to  be  used 
in  connection  with  or  relating  to  all  viruses,  serums, 
toxins,  and  analogous  products  prepared  therein,  shall 
accompany  the  application  for  a  license,  unless  these 


252  HOG   CHOLEEA 

plans,  specifications,  labels,  and  advertising  matter  have 
already  been  approved  in  writing  by  the  bureau. 

Paragraph  3.  In  case  of  change  in  ownership  or  loca- 
tion while  an  application  is  pending,  or  after  a  license 
has  been  issued,  a  new  application  shall  be  made. 

SECTION  4.  Paragraph  1.  A  license  will  not  be  issued 
unless  the  condition  of  the  establishment  and  the  methods 
of  preparation  are  such  as  reasonably  to  insure  that  the 
product  will  accomplish  the  object  for  which  it  is  in- 
tended and  that  such  product  is  not  worthless,  contamin- 
ated, dangerous,  or  harmful. 

Paragraph  2.  A  license  will  not  be  issued  unless  and 
until  the  establishment  is  prepared  to  operate  under 
the  direct  supervision  of  a  competent  person  trained  in 
bacteriological  technique  and  in  the  preparation  of 
viruses,  serums,  toxins,  or  analogous  products  named  in 
the  application. 

Paragraph  3.  A  license  will  not  be  issued  for  the 
preparation  of  any  virus,  serum,  toxin,  or  analogous 
product  if  advertised  so  as  to  mislead  or  deceive  the  pur- 
chaser, or  if  the  package  or  container  in  which  the  same 
is  intended  to  be  sold,  bartered,  exchanged,  or  shipped 
bears  or  contains  any  statement,  design,  or  device  which 
is  false  or  misleading  in  any  particular. 

SECTION  5.  Paragraph  1.  A  license  will  be  issued 
only  after  inspection  of  the  establishment  by  a  bureau 
employee  has  shown  that  the  condition  and  equipment 
of  the  establishment  and  the  methods  of  preparing,  han- 
dling, and  storing  are  in  conformity  with  these  regula- 
tions. 

Paragraph  2.  Licenses  shall  be  numbered  and  shall  be 
in  the  following  form : 

UNITED  STATES  VETERINARY  LICENSE  No 

WASHINGTON,  D.  C., ,  19 . . 

This  is  to  certify  that,  pursuant  to  the  terms  of  the  act 
Of  Congress  approved  March  4,  1913  (37  Stat.,  832), 


APPENDIX  253 

governing  the  preparation,  sale,  barter,  exchange,  ship- 
ment, and  importation  of  viruses,  serums,  toxins,  and 
analogous  products  intended  for  use  in  the  treatment  of 

domestic  animals,   is 

hereby  licensed  to  maintain  at Street, 

city  or  town  of ,  State  of , 

an  establishment  for  the  preparation  of 

during  the  calendar  year  19 .... 

This  license  is  subject  to  suspension  or  revocation  if 
the  licensee  violates  or  fails  to  comply  with  any  provision 
of  said  act  approved  March  4,  1913,  or  of  the  regulations 
made  thereunder. 


Secretary  of  Agriculture. 
Countersigned : 


Chief,  Bureau  of  Animal  Industry. 

Two  or  more  licenses  may  bear  the  same  number  when 
they  are  issued  to  firms  under  the  same  ownership  or 
control,  provided  a  serial  letter  is  added  when  necessary, 
to  identify  each  license. 

Paragraph  3.  Each  license  shall  teminate  at  the  end 
of  the  calendar  year  for  which  it  is  issued. 

SECTION  6.  Paragraph  1.  No  viruses,  serums,  toxins, 
or  analogous  products  shall  be  prepared  in  whole  or  in 
part  in  a  licensed  establishment  by  any  other  licensed 
establishment  unless  authorized  in  advance  by  the  chief 
of  bureau. 

Paragraph  2.  Each  licensed  establishment  shall  be 
separate  and  distinct  from  any  unlicensed  establishment 
in  which  any  virus,  serum,  toxin,  or  analogous  product 
is  prepared  or  handled. 

Paragraph  3.  When  a  license  is  issued  the  bureau 
shall  inform  the  proprietor  or  operator  of  the  establish- 
ment of  the  requirements  of  these  regulations.  If  the 
establishment  at  the  time  the  license  is  issued  contains 
any  viruses,  serums,  toxins,  or  analogous  products,  which 


254  HOG    CHOLEEA 

have  not  theretofore  been  prepared,  and  of  which  the 
containers  have  not  been  theretofore  marked,  in  com- 
pliance with  these  regulations,  the  identity  of  the  same 
shall  be  maintained  and  they  shall  not  be  shipped  or 
delivered  for  shipment  from  any  State  or  Territory  or 
the  District  of  Columbia  to  any  other  State  or  Terri- 
tory or  the  District  of  Columbia,  or  otherwise  dealt  with 
as  products  prepared  under  these  regulations.  The  es- 
tablishment shall  adopt  and  enforce  all  necessary  meas- 
ures, and  shall  comply  with  all  such  directions  as  the 
chief  of  bureau  may  prescribe  for  carrying  out  the  pur- 
poses of  this  paragraph. 

REGULATION  3. — PERMITS 

SECTION  1.  Each  importer  of  viruses,  serums,  toxins, 
or  analogous  products  shall  hold  an  unexpired,  unsus- 
pended,  and  unrevoked  permit  issued  by  the  Secretary 
of  Agriculture. 

SECTION  2.  Paragraph  1.  Each  importer  of  viruses, 
serums,  toxins,  and  analogous  products  shall  make  appli- 
cation in  writing  to  the  Secretary  of  Agriculture  for  a 
permit.  The  application  shall  specify  the  port  or  ports 
of  entry  at  which  the  imported  articles  will  be  cleared 
through  the  customs.  Blank  forms  of  application  will 
be  furnished  upon  request  addressed  to  the  Bureau  of 
Animal  Industry,  Washington,  D.  C. 

Paragraph  2.  Each  application  for  a  permit  shall  be 
accompanied  by  the  affidavit  of  the  actual  manufacturer 
produced  before  an  American  consular  officer,  giving 
the  city  or  town  where  the  viruses,  serums,  toxins,  or 
analogous  products  mentioned  therein  are  prepared,  and 
stating  that  said  products  are  not  worthless,  contami- 
nated, dangerous,  or  harmful,  whether  the  products  were 
derived  from  animals,  and  if  so  derived,  that  such  ani- 
mals had  not  been  exposed  to  any  infectious  or  conta- 
gious disease,  except  as  may  have  been  essential  in  the 


APPENDIX  255 

preparation  of  the  products  and  as  specified  in  the  affi- 
davit. 

Paragraph  3.  Each  application  for  a  permit  shall  be 
accompanied  by  the  written  consent  of  the  actual  manu- 
facturer that  properly  accredited  employees  of  the  de- 
partment shall  have  the  privilege  of  inspecting1,  without 
previous  notification,  all  parts  of  the  establishment  at 
which  such  viruses,  serums,  toxins,  or  analogous  prod- 
ucts are  prepared,  and  all  processes  of  and  all  records 
kept  relative  to  the  preparation  of  such  products  at 
such  times  as  may  be  demanded  by  the  aforesaid  em- 
ployees. 

Paragraph  4.  Each  application  for  permit  shall  be 
accompanied  by  triplicate  copies  of  all  labels  and  adver- 
tising matter. 

SECTION  3.  A  permit  will  not  be  issued  for  the  impor- 
tation of  any  viruses,  serums,  toxins,  or  analogous  prod- 
ucts if  advertised  so  as  to  mislead  or  deceive  the  pur- 
chaser, or  if  the  package  or  container  in  which  the  same 
is  intended  to  be  sold,  bartered,  exchanged,  shipped,  or 
imported,  bears  or  contains  any  statement,  design,  or 
device  which  is  false  or  misleading  in  any  particular. 

SECTION  4.  Paragraph  1.  Permits  shall  be  numbered 
and  shall  be  in  the  following  form : 

UNITED  STATES  VETERINARY  PERMIT  No 

WASHINGTON,  D.  C., ,  19 ... 

This  is  to  certify  that,  pursuant  to  the  terms  of  the  act 
of  Congress  approved  March  4,  1913  (37  Stat.,  832), 
governing  the  preparation,  sale,  barter,  exchange,  ship- 
ment, and  importation  of  viruses,  serums,  toxins,  and 
analogous  products  intended  for  use  in  the  treatment  of 

domestic  animals, ,  of 

,  State  of ,  is  hereby 

authorized,  so  far  as  the  jurisdiction  of  the  Department 

of  Agriculture  is  concerned,  to  import 

manufactured  by ,  of 

,  into  the  United  States  through  the  port 


256  HOG    CHOLERA 

of    during  the   calendar  year 

19.... 

This  permit  is  subject  to  suspension  or  revocation  if 
the  permittee  violates  or  fails  to  comply  with  the  pro- 
visions of  the  said  act  approved  March  4,  1913,  or  of  the 
regulations  made  thereunder. 


Secretary  of  Agriculture. 
Countersigned : 


Chief,  Bureau  of  Animal  Industry. 

Paragraph  2.  Each  permit  shall  terminate  at  the  end 
of  the  calendar  year  for  which  it  is  issued. 

REGULATION  4. — SUSPENSION   OB  REVOCATION   OP  LICENSES 
AND  PERMITS 

SECTION  1.  Licenses  or  permits  may  be  suspended  or 
revoked  after  opportunity  for  hearing  has  been  accorded 
the  licensee  or  permittee  if  it  appears — 

(1)  That   the   construction   of  the   establishment   in 
which  the  viruses,  serums,  toxins,  or  analogous  products 
are  prepared  is  defective,  or  that  the  establishment  is 
improperly  conducted ; 

(2)  That  the  methods  of  preparation  are  faulty,  or 
that  the  said  products  contain  impurities  or  lack  po- 
tency ; 

(3)  That  the  products  are  labeled  so  as  to  mislead  or 
deceive  the  purchaser  in  any  particular; 

(4)  That  the  license  or  permit  is  used  to  facilitate  or 
effect  the  preparation,  sale,  barter,  exchange,  shipment, 
or  importation  of  any  worthless,  contaminated,  danger- 
ous,  or  harmful  viruses,  serums,   toxins,   or   analogous 
products;  or 

(5)  That  the  licensee  or  permittee  has  violated  or 
failed  to  comply  with  any  provision  of  the  virus-serum- 
toxin  act  of  1913,  or  of  the  rules  and  regulations  made 
thereunder. 


APPENDIX  257 

SECTION  2.  All  hearings  shall  be  private  and  at  times 
and  places  designated  by  the  Secretary  of  Agriculture. 
The  parties  interested  may  appear  in  person  or  by  at- 
torney, and  may  submit  oral  or  written  evidence  on  the 
questions  involved.  Upon  request  and  by  paying  the 
cost,  the  person  involved  will  be  furnished  with  a  copy 
of  the  transcript  of  the  hearing. 

REGULATION   5. — NOTICE  TO  LICENSEES  AND  PERMITTEES 

SECTION  1.  If  at  any  time  it  appears  that  the  prepa- 
ration, sale,  barter,  exchange,  shipment,  or  importation 
of  any  virus,  serum,  toxin,  or  analogous  product  by  any 
person  holding  a  license  or  permit  may  be  dangerous  in 
the  treatment  of  domestic  animals,  the  Secretary  of 
Agriculture  will  so  notify  the  licensee  or  permittee,  and 
unless  and  until  the  Secretary  of  Agriculture  shall  oth- 
erwise direct,  no  person,  so  notified,  shall  thereafter  pre- 
pare, sell,  barter,  or  exchange,  nor  shall  thereafter  ship, 
offer  for  shipment,  or  import  any  of  such  product. 

REGULATION    6. — ASSIGNMENT    OF    BUREAU   EMPLOYEES 

SECTION  1.  Any  bureau  employee,  as  defined  in  these 
regulations,  shall  be  permitted  to  enter  any  establish- 
ment licensed  under  these  regulations  at  any  hour  dur- 
ing the  daytime  or  nighttime ;  and  such  bureau  employee 
shall  be  permitted  to  inspect  without  previous  notifica- 
tion the  entire  premises  of  the  establishment,  including 
all  buildings,  compartments,  and  other  places,  and  all 
equipment  such  as  chemicals,  instruments,  apparatus, 
and  the  like,  as  well  as  the  methods  used  in  the  manu- 
facture of,  and  all  records  maintained  relative  to  viruses, 
serums,  toxins,  or  analogous  products. 

SECTION  2.  Each  bureau  employee,  as  defined  in  these 
regulations,  will  be  furnished  with  a  numbered  official 
badge,  which  he  shall  not  allow  to  leave  his  possession. 
This  badge  shall  be  sufficient  identification  to  entitle  him 


258  HOG    CHOLERA 

to  admittance  at  all  regular  entrances  and  to  all  parts  of 
the  licensed  establishment  and  premises  and  to  any  place 
at  any  time1  for  the  purpose  of  making  an  inspection 
pursuant  to  section  1  of  this  regulation. 

REGULATION   7. — FACILITIES   FOR  INSPECTION 

SECTION  1.  When  required  by  the  chief  of  bureau  or 
the  inspector  in  charge,  the  following  facilities,  and  such 
others  as  may  be  essential  to  efficient  conduct  of  inspec- 
tion, shall  be  furnished  by  each  licensed  establishment: 

(a)  Satisfactory  pens,  equipment,  and  assistance  for 
conducting  tests  required  in  accordance  with  these  regu- 
lations. 

(&)  Suitable  rooms,  compartments,  or  receptacles  in 
such  number  and  places  as  may  be  necessary  for  holding 
any  viruses,  serums,  toxins,  or  analogous  products  for 
treatment  or  testing  required  in  accordance  with  these 
regulations.  Such  rooms,  compartments,  or  receptacles 
shall  be  equipped  for  secure  locking  and  shall  be  held 
under  locks  furnished  by  the  department,  and  the  keys 
of  such  locks  shall  not  leave  the  custody  of  bureau  em- 
ployees. 

REGULATION   8. — SANITATION 

SECTION  1.  Paragraph  1.  Triplicate  copies  of  plans 
properly  drawn  to  scale,  and  of  specifications,  including 
plumbing  and  drainage,  for  remodeling  plants  of  licensed 
establishments  and  for  new  structures,  should  be  sub- 
mitted to  the  chief  of  bureau  in  advance  of  construction. 

Paragraph  2.  Stables  or  other  premises  for  animals 
used  in  the  production  or  testing  of  viruses,  serums,  tox- 
ins, or  analogous  products  shall  be  properly  ventilated 
and  lighted,  appropriately  drained  and  guttered,  and 
kept  in  good  sanitary  condition. 

Paragraph  3.  Animals  infected  with  or  exposed  to 
any  infectious,  contagious,  or  communicable  disease  shall 
be  properly  segregated. 


APPENDIX  259 

Paragraph  4.  Licensed  establishments  shall  be  so  lo- 
cated as  to  avoid  the  spread  of  disease,  and  suitable 
arrangements  shall  be  made  for  the  disposal  of  all 
refuse. 

Paragraph  5.  Direct  communication  to  licensed  es- 
tablishments shall  not  be  maintained  from  public  stock- 
yards, abattoir  pens,  or  other  places  in  which  animals 
are  received  or  held  for  any  purpose. 

Paragraph  6.  All  viruses,  serums,  toxins,  and  analo- 
gous products  shall  be  prepared,  handled,  and  distrib- 
uted with  due  sanitary  precautions,  and  all  viruses, 
serums,  toxins,  or  analogous  products  shipped  or  deliv- 
ered for  shipment  shall  be  securely  packed. 

SECTION  2.  Paragraph  1.  The  floors,  walls,  ceilings, 
partitions,  posts,  doors,  and  all  other  parts  of  all  struc- 
tures at  licensed  establishments  shall  be  of  such  material, 
construction,  and  finish  as  can  be  readily  and  thoroughly 
cleaned. 

Paragraph  2.  Separate  rooms  or  compartments  shall 
be  provided  for  preparing,  handling,  and  storing  viru- 
lent or  attenuated  micro-organisms  or  toxins. 

Paragraph  3.  All  rooms  and  compartments  shall  have 
abundant  light  and  sufficient  ventilation  to  insure  sani- 
tary and  hygienic  conditions. 

SECTION  3.  Paragraph  1.  Each  licensed  establish- 
ment shall  have  dressing  rooms  and  toilet  rooms  and 
urinals  sufficient  in  number,  ample  in  size,  conveniently 
located,  properly  ventilated,  and  meeting  all  require- 
ments as  to  sanitary  construction  and  equipment.  These 
shall  be  separate  from  rooms  and  compartments  in  which 
any  viruses,  serums,  toxins,  or  analogous  products  are 
prepared,  handled,  or  stored. 

Paragraph  2.  Each  licensed  establishment  shall  have 
modern  lavatory  accommodations,  including  running  hot 
and  cold  water,  soap,  towels,  and  the  like.  These  shall 
be  located  at  such  places  in  establishments  as  may  be 


260  HOG   CHOLERA 

essential  to  assure  cleanliness  of  all  persons  handling 
viruses,  serums,  toxins,  or  analogous  products. 

SECTION  4.  There  shall  be  an  efficient  drainage  and 
plumbing  system  for  the  establishment  and  premises, 
and  all  drains  and  gutters  shall  be  properly  installed 
with  approved  traps  and  vents. 

SECTION  5.  The  water  supply,  both  hot  and  cold,  shall 
be  ample  and  clean.  Adequate  facilities  shall  be  pro- 
vided for  the  distribution  of  water  in  each  establish- 
ment and  for  the  washing  of  all  equipment,  containers, 
machinery,  instruments,  other  apparatus,  and  animals 
used  in  the  preparation,  handling,  or  storing  of  any 
viruses,  serums,  toxins,  or  analogous  products. 

SECTION  6.  All  equipment,  containers,  instruments, 
and  other  apparatus  used  in  the  preparation,  handling, 
or  storing  of  any  virus,  serum,  toxin,  or  analogous  prod- 
uct shall  be  of  such  material,  construction,  and  design 
as  can  be  readily  and  thoroughly  cleaned  and  sterilized, 
and  such  equipment,  containers,  instruments,  and  other 
apparatus  shall  be  handled  so  as  to  insure  freedom  from 
contamination.  Equipment,  containers,  instruments,  and 
other  apparatus  used  for  preparing,  handling,  or  stor- 
ing virulent  or  attenuated  micro-organisms  or  toxins 
shall  not  be  used  for  handling,  preparing,  Or  storing 
other  forms  of  biological  products. 

SECTION  7.  All  employees  of  the  establishment  who 
handle  viruses,  serums,  toxins,  or  analogous  products 
shall  keep  their  hands  and  clothing  clean.  The  hands 
of  such  employees  shall  not  come  into  contact  with  any 
viruses,  serums,  toxins,  or  analogous  products,  or  with 
any  part  of  the  equipment,  containers,  instruments,  or 
other  apparatus,  which  after  sterilization  may  come  into 
contact  with  any  such  products. 

SECTION  8.  Caps,  gowns,  and  other  outer  clothing 
worn  by  persons  while  handling  any  viruses,  serums, 
toxins,  or  analogous  products,  or  by  those  who  enter 


APPENDIX  ,  261 

any  room,  compartment,  or  place  where  any  such  prod- 
ucts are  being  handled,  shall  be  of  clean,  white  material 
whenever  practicable. 

SECTION  9.  The  outer  premises  of  every  licensed  es- 
tablishment, embracing  docks,  driveways,  approaches, 
yards,  pens,  chutes,  and  alleys,  shall  be  properly  drained 
and  kept  in  a  clean  and  orderly  condition.  The  accumu- 
lation on  the  premises  of  an  establishment  of  any  ma- 
terial in  which  flies  may  breed  is  forbidden.  No  nuisance 
shall  be  allowed  in  any  licensed  establishment  or  on  its 
premises. 

SECTION  10.  Every  practicable  precaution  shall  be 
taken  to  keep  establishments  free  of  flies,  rats,  mice,  and 
other  vermin. 

SECTION  11.  All  parts  of  the  carcasses  of  animals  pro- 
ducing viruses,  all  dead  animals,  all  refuse,  and  all 
worthless,  contaminated,  dangerous,  or  harmful  viruses, 
serums,  toxins,  or  analogous  products,  shall  be  inciner- 
ated or  otherwise  destroyed  by  establishments  in  accord- 
ance with  methods  approved  by  the  chief  bureau. 

SECTION  12.  All  rooms,  compartments,  and  other 
places  used  for  preparing,  handling,  or  storing  viruses, 
serums,  toxins,  or  analogous  products  shall  be  kept  clean 
and  sanitary,  and  all  equipment,  containers,  instruments, 
and  other  apparatus  used  in  preparing,  handling,  or 
storing  any  such  products  shall  be  thoroughly  cleaned 
and  sterilized  before  use. 

SECTION  13.  Smoking  or  expectorating  in  any  room, 
compartment,  or  place  in  which  viruses,  toxins,  or  analo- 
gous products  are  prepared,  handled,  or  stored  is  pro- 
hibited. 

REGULATION   9. — STERILIZATION 

SECTION  1.  Paragraph  1.  All  equipment,  containers, 
instruments,  and  other  apparatus,  before  being  used  in 
preparing,  handling,  or  storing  viruses,  serums,  toxins, 
or  other  analogous  products,  except  as  prescribed  in  the 


262  HOG   CHOLEEA 

following  paragraph,  shall  be  thoroughly  sterilized  by 
live  steam  at  a  temperature  of  at  least  120°  C.  for  not 
less  than  one-half  hour,  or,  by  dry  heat  at  a  temperature 
of  at  least  160°  C.  for  not  less  than  one  hour.  If  for  any 
reason  such  methods  of  sterilization  are  impracticable, 
then  a  process  known  to  be  equally  efficacious  in  de- 
stroying microorganisms  and  their  spores  may  be  sub- 
stituted after  approval  by  the  chief  of  bureau. 

Paragraph  2.  Instruments  used  in  connection  with 
the  bleeding  of  virus  pigs  and  hyperimmune  hogs,  and 
other  like  equipment,  of  establishments  manufacturing 
hog-cholera  virus  and  anti-hog-cholera  serum,  which  are 
found  to  be  damaged  by  exposure  to  the  degree  of  heat 
prescribed  in  the  preceding  paragraph,  after  having  been 
thoroughly  cleaned,  may  be  sterilized  by  boiling  for  not 
less  than  15  minutes,  provided  apparatus,  satisfactory 
to  the  inspector  in  charge,  is  furnished  for  this  purpose. 

REGULATION  10. — STORAGE 

SECTION  1.  Viruses,  serums,  toxins,  and  analogous 
products  which  may  be  injuriously  affected  by  exposure 
to  light  or  to  high  temperature  shall  be  stored  in  a  dark, 
cold  chamber  or  refrigerator  at  a  temperature  of  not  to 
exceed  55°  F.  All  dealers  in  the  District  of  Columbia 
or  any  Territory  or  in  any  place  under  the  jurisdiction 
of  the  United  States  shall  keep  such  products  protected 
from  light  and  under  refrigeration  until  sold  or  other- 
wise disposed  of. 

REGULATION  11. — RECORDS 

SECTION  1.  Paragraph  1.  Permanent  detailed  rec- 
ords of  the  sources,  of  the  preparation,  of  tests  for  purity 
and  potency,  and  of  methods  of  preservation,  of  each 
batch  of  virus,  serum,  toxin,  and  analogous  products 
shall  be  kept  by  each  licensed  establishment  and  by  each 


APPENDIX  263 

manufacturer  producing  such  products  for  importation 
into  the  United  States. 

Paragraph  2.  Permanent  detailed  records,  in  a  form 
satisfactory  to  the  chief  of  bureau,  shall  be  maintained 
by  each  licensed  establishment  and  by  each  importer, 
showing  the  sale,  shipment,  or  other  disposition  of  the 
viruses,  serums,  toxins,  and  analogous  products  handled. 

REGULATION  12. — LABELS 

SECTION  1.  Paragraph  1.  Each  immediate  or  true 
container  of  viruses,  serums,  toxins,  or  analogous  prod- 
ucts, prepared  for  sale,  barter,  exchange,  or  shipment, 
by  any  licensed  establishment,  or  imported  into  the 
United  States,  shall  bear  a  trade  label  as  hereinafter  de- 
scribed. 

Paragraph  2.  No  container  of  virus,  serum,  toxin,  or 
analogous  product  shall  bear  a  trade  label  unless  and 
until  the  product  contained  therein  shall  have  been  pre- 
pared in  compliance  with  these  regulations  and  found 
not  to  be  worthless,  contaminated,  dangerous,  or  harm- 
ful. 

Paragraph  3.  No  person  shall  apply  or  affix,  or  cause 
to  be  applied  or  affixed,  any  trade  label,  stamp,  or  mark, 
to  any  container  of  hog-cholera  virus,  or  anti-hog- 
cholera  serum,  prepared  or  received  in  a  licensed  estab- 
lishment except  in  compliance  with  these  regulations. 
Suitable  tags  or  labels  of  a  distinct  design  should  be 
used  for  identifying  all  biologies  while  in  course  of 
preparation. 

SECTION  2.  Paragraph  1.  Trade  labels  shall  bear  the 
true  name  of  the  product  contained  in  the  package,  the 
name  and  address  of  the  manufacturer  except  as  other- 
wise provided  in  paragraph  7  of  this  section,  and  the 
license  or  permit  number  assigned  by  the  department. 
The  license  number  and  permit  number  shall  be  shown 
in  either  of  the  following  forms,  respectively:  "U.  S. 


264  HOG   CHOLEKA 

Veterinary  License  No. 

No.  -    — ,"  and  "U.  S.  Veterinary  Permit  No.  -    — ," 

or  "U.  S.  Vet.  Permit  No. ."    Such  labels  shall  bear 

all  other  information  required  by  the  chief  of  bureau  and 
may  also  bear  any  other  statement  not  false  or  mislead- 
ing and  which  has  been  approved  by  the  bureau. 

Paragraph  2.  Each  trade  label  shall  bear  a  serial 
number,  affixed  by  the  manufacturer,  by  which  the  prod- 
uct can  be  identified  with  the  records  of  preparation. 

Paragraph  3.  Each  trade  label  shall  bear  a  return 
date  affixed  before  the  product  is  removed  from  the 
establishment.  The  date  shown  shall  be  a  date  after 
which  the  manufacturer  does  not  guarantee  the  product 
to  be  of  full  strength  or  potency. 

Paragraph  4.  All  trade  labels  affixed  to  or  used  in 
connection  with  each  immediate  or  true  container  shall 
bear  a  dosage  table  and  full  instructions  governing  the 
use  of  the  product. 

Paragraph  5.  Trade  labels  affixed  to  the  immediate 
or  true  containers  of  viruses  and  products  prepared 
from  attenuated  organisms  shall  bear,  in  addition  to  the 
statements  required  by  the  preceding  paragraphs  of  this 
section,  the  following,  prominently  placed  and  lettered : 
"  CAUTION — BURN  THIS  CONTAINER  AND  ALL  UNUSED 
CONTENTS." 

Paragraph  6.  When  any  virus,  serum,  toxin,  or  analo- 
gous product  is  prepared  by  a  licensed  establishment  or 
imported  for  a  person  other  than  the  one  to  whom  a 
license  or  permit  has  been  issued  and  the  name  and  ad- 
dress of  the  distributor  as  well  as  that  of  the  manufac- 
turer is  to  appear  on  the  label  of  the  container  thereof, 
a  statement  shall  be  made  on  the  label  to  the  effect  that 
the  virus,  serum,  toxin,  or  analogous  product  is  dis- 
tributed by  such  person.  The  term,  "  Distributer, " 
"Distributers,"  "Distributed  by,"  or  other  equivalent 
terms  may  be  used,  if  prominentlyjplaced  and  lettered 


APPENDIX  265 

in  connection  with  the  name  and  address  of  the  distrib- 
uting person,  provided  the  same  are  not  used  so  as  to  be 
either  false  or  misleading. 

Paragraph  7.  The  name  and  address  of  the  manufac- 
turer may  be  omitted  from  trade  labels  when  any  virus, 
serum,  toxin,  or  analogous  product  is  to  be  distributed  by 
a  person  other  than  the  manufacturer,  provided  the 
name  and  address  of  the  distributor  appears  on  such 
trade  labels  in  immediate  connection  with  a  statement 
showing  the  license  under  which  the  product  was  manu- 
factured. This  statement,  together  with  the  name  and 
address  of  the  distributor,  shall  appear  in  letters  of  uni- 
form size  and  character,  and  be  in  the  following  form: 

"Produced  under  U.  S.  Veterinary  License  No.  . 

Distributed  by  -  -  (name  and  address  of  distributor) . ' ' 

Paragraph  8.  Copies  of  all  trade  labels  before  use 
shall  be  submitted  to  the  bureau  for  examination  and 
approval.  These  labels  shall  be  submitted  in  triplicate, 
quadruplicate,  or  quintuplicate,  as  may  be  indicated. 
Triplicate  copies  of  new  trade  labels  in  the  form  of 
sketches,  proofs,  or  photographic  copies  should  be  sub- 
mitted, through  the  inspector  in  charge,  to  the  bureau 
for  approval. 

REGULATION   13. — COLLECTING   SAMPLES 

SECTION  1.  Paragraph  1.  Samples  of  viruses,  serums, 
toxins,  and  analogous  products" shall  be  collected  by  au- 
thorized officers,  agents,  or  employees  of  the  department. 

Paragraph  2.  Samples  may  be  purchased  in  the  open 
market  and  the  marks,  brands,  or  tags  upon  the  package 
or  wrapper  thereof  shall  be  noted.  The  collector  shall 
note  the  names  of  the  vendor  and  agent  of  the  vendor 
who  made  the  sale,  together  with  the  date  of  purchase. 
The  collector  shall  purchase  representative  samples. 

Paragraph  3.  All  samples  or  parts  of  samples  shall  be 
sealed  by  the  collector  and  marked  with  identifying 
marks. 


266  HOG   CHOLEEA 


REGULATION   14. — TESTING 

SECTION  1.  Except  as  otherwise  provided  in  these 
regulations,  all  viruses,  serums,  toxins,  and  analogous 
products  shall  be  prepared,  handled,  stored,  marked, 
treated,  and  tested  by  licensed  establishments  in  accord- 
ance with  methods  prescribed  by  the  Chief  of  the  Bu- 
reau of  Animal  Industry. 

REGULATION    15. — RETESTING 

SECTION  1.  Viruses,  serums,  toxins,  and  analogous 
products,  the  containers  of  which  bear  United  States 
veterinary  license  numbers  or  United  States  veterinary 
permit  numbers,  or  any  other  mark  required  by  these 
regulations,  shall  be  subject  to  inspection  at  any  time  or 
place.  If  it  appears  as  a  result  of  such  inspection  that 
any  such  product,  even  though  prepared  in  a  licensed 
establishment  or  imported  under  permit  issued  by  the 
Secretary,  is  worthless,  contaminated,  dangerous,  or 
harmful,  the  Secretary  shall  give  notice  thereof  to  the 
manufacturer  or  importer  and  to  any  jobbers,  dealers, 
or  other  persons  known  to  have  any  of  such  product  in 
their  possession.  Unless  and  until  the  Secretary  shall 
otherwise  direct,  no  person  so  notified  shall  thereafter 
sell,  barter,  or  exchange  in  any  place  under  the  jurisdic- 
tion of  the  United  States  nor  shall  thereafter  ship  or 
deliver  for  shipment  from  any  States,  Territory,  or  the 
District  of  Columbia  to  any  other  State,  Territory,  or 
the  District  of  Columbia,  any  of  such  product. 

REGULATION  16. — REPORTS 

SECTION  1.  Paragraph  1.  Reports  of  the  work  of  in- 
spection carried  on  in  every  licensed  establishment  shall 
be  forwarded  to  the  bureau  by  the  inspector  in  charge 
in  such  form  and  manner  as  may  be  specified  by  the 
chief  of  bureau. 


APPENDIX  267 

Paragraph  2.  Each  licensed  establishment  shall  fur- 
nish to  the  bureau  employees  accurate  information  as  to 
all  matters  needed  by  them  for  making  their  reports 
pursuant  to  paragraph  1  of  this  section. 

REGULATION  17. — ANIMALS 

SECTION  1.  Paragraph  1.  Licensed  establishments 
which  procure  animals  from  public  stockyards,  abattoir 
pens,  or  similar  places  shall  afford  opportunity  for  all 
hogs,  cattle,  sheep,  and  goats  admitted  to  the  premises 
of  such  establishments  to  range  in  contact  with  other 
animals  as  prescribed  in  section  3  of  this  regulation. 

Paragraph  2.  Cattle,  sheep,  and  goats  from  whatever 
source,  except  calves  procured  under  the  provisions  of 
section  5  of  this  regulation  and  used  for  testing  hog- 
cholera  virus  to  determine  its  freedom  from  foot-and- 
mouth  disease,  admitted  to  the  premises  of  licensed  es- 
tablishments shall  be  afforded  opportunity  to  range  in 
contact  with  other  animals  as  prescribed  in  section  3  of 
this  regulation. 

SECTION  2.  Paragraph  1.  Licensed  establishments 
shall  provide  suitable  pens  to  be  known  as  "  Receiving 
pens"  through  which  all  hogs,  cattle,  sheep,  and  goats 
shall  pass  in  accordance  with  the  provisions  of  this 
regulation  before  they  shall  be  admitted  to  any  other 
part  of  the  premises. 

Paragraph  2.  Licensed  establishments  shall  provide 
healthy  calves  in  thrifty  condition  and  ranging  from  3 
to  12  months  of  age  for  use  as  contact  animals  in  re- 
ceiving pens.  They  shall  be  referred  to  as  "contact 
calves. ' ' 

Paragraph  3.  Each  contact  calf  shall  have  the  left 
ear  thereof  pierced  with  a  hole  not  less  than  %  inch  in 
diameter  and  to  the  right  ear  of  each  animal  shall  be 
attached  a  serially  numbered  metal  tag. 

SECTION  3.    Paragraph  1.    All  hogs  susceptible  to  hog 


268  HOG   CHOLEEA 

cholera  which  are  admitted  to  the  premises  of  licensed 
establishments  under  the  provisions  of  section  1,  para- 
graph 1,  of  this  regulation  shall  be  held  in  receiving 
pens  for  at  least  24  hours  after  admission  to  the  premises 
and  during  this  time  they  shall  be  allowed  free  range 
and  contact  with  not  less  than  4  contact  calves  for  each 
lot  of  200  hogs  or  less  in  the  receiving  pens. 

Paragraph  2.  Hogs  which  are  immune  to  hog  cholera, 
admitted  to  the  premises  of  licensed  establishments  un- 
der the  provisions  of  section  1,  paragraph  1,  of  this 
regulation,  shall  be  held  in  receiving  pens  with  contact 
calves  as  prescribed  in  the  preceding  paragraph  for  at 
least  48  hours. 

Paragraph  3.  All  animals  covered  by  section  1,  of  this 
regulation,  except  hogs,  shall  be  held  in  receiving  pens 
for  at  least  48  hours  as  prescribed  in  paragraph  1,  of 
this  section,  except  that  not  less  than  two  contact  calves 
shall  be  used  for  each  lot  of  20  animals  or  less  in  the 
same  pen. 

SECTION  4.  Paragraphl.  All  surviving  contact  calves 
shall  be  held  in  the  receiving  pens  of  licensed  establish- 
ments for  at  least  one  month  and  not  to  exceed  four 
months  from  date  of  admission  to  receiving  pens  as 
contact  calves. 

Paragraph  2.  Removal  of  contact  calves  from  receiv- 
ing pens  shall  be  so  arranged  that  a  rotation  will  be  es- 
tablished whereby  one  of  the  animals  will  be  replaced  at 
intervals  of  one  month  and  the  entire  group  replaced 
every  four  months  or  less. 

Paragraph  3.  Removal  of  contact  calves  from  receiv- 
ing pens  shall  be  accomplished  so  that  the  animals  last 
furnished  for  the  purpose  may  be  used  for  the  maximum 
time  permitted  by  the  preceding  paragraphs  of  this 
section.  No  contact  calf  shall  be  used  as  such  more  than 
once. 

Paragraph  4.     Contact  calves  shall  be  carefully  ob- 


APPENDIX  269 

served  by  a  veterinary  inspector  as  frequently  as  may 
be  necessary  to  detect  evidence  of  disease. 

SECTION  5.  Establishments  licensed  to  prepare  anti- 
hog-cholera  serum  or  hog-cholera  virus  which  do  not 
procure  animals  from  public  stockyards,  abattoir  pens, 
or  similar  places,  shall  furnish  a  properly  executed  cer- 
tificate according  to  the  following  form  covering  each 
lot  or  shipment  of  animals  offered  for  admission  to  the 
premises  thereof.  These  certificates  shall  be  signed  by 
an  authorized  representative  of  the  licensed  establish- 
ment. 

,19... 

This  is  to  certify  that 

)C  1^S  I  wnick  are  °ffere(l  f°r  admission  to  the  estab- 
lishment of  the  Company,  are 

from  the  farm  or  premises  of ,  in  the 

State  of ,  county  of ,  town- 
ship of ,  and  to  the  best  of  our 

knowledge  and  belief  were  on  said  farm  or  premises  at 
least  21  days  prior  to  this  date,  and  were  not  exposed  to 
any  infectious,  contagious,  or  communicable  disease,  and 
no  new  stock  was  brought  on  to  the  said  farm  or  premises 
during  that  time.  The  said  animals  have  not  been  in  or 
transported  through  any  public  stockyards,  abattoir 
pens,  or  similar  places,  nor  have  they  been  exposed  to 
any  infectious,  contagious,  or  communicable  disease  since 
their  removal  from  said  farm  or  premises. 

(Signed)       •.  Co., 

Per 

SECTION  6.  Paragraph  1.  All  animals  presented  for 
admission  to  the  premises  of  establishments  licensed  to 
prepare  hog-cholera  virus  or  anti-hog-cholera  serum  shall 
be  examined  by  a  veterinary  inspector  as  soon  as  prac- 
ticable after  they  are  received  and  before  their  re- 
moval from  the  receiving  pens  in  order  to  determine 


270  HOG   CHOLERA 

their  physical  condition.  No  animal  shall  be  removed 
from  receiving  pens  without  examination  by  and  the 
permission  of  a  veterinary  inspector. 

Paragraph  2.  After  examination,  if  the  animals  are 
permitted  to  remain  upon  the  premises  and  to  gain  en- 
trance to  the  holding  pens  of  the  establishment,  they 
shall  be  given  serially  numbered  metal  tags,  either  prior 
to  or  at  the  time  of  inoculation  or  hyperimmunization. 

Paragraph  3.  All  tags  used  for  the  identification  of 
animals  shall  be  attached  to  the  ears  of  the  animals  in 
a  manner  satisfactory  to  the  inspector  in  charge.  The 
tags  so  attached  shall  be  the  means  of  assisting  in  identi- 
fying the  animals  so  long  as  they  remain  on  the  premises. 

Paragraph  4.  All  tags  which  are  used  to  identify  ani- 
mals shall  be  furnished  and  attached  by  the  licensed 
establishment,  and  when  said  tags  are  not  in  actual  use 
they  shall  at  all  times  be  held  in  the  custody  of  a  bureau 
employee. 

Paragraph  5.  When  practicable,  the  left  ear  of  each 
animal  used  in  testing  the  purity  and  potency  of  viruses, 
serums,  toxins,  and  analogous  products  shall  be  pierced 
with  a  hole  not  less  than  three-fourths  of  an  inch  in 
diameter.  Animals  bearing  marks  of  the  above-de- 
scribed character  shall  not  be  used  more  than  once  by 
licensed  establishments  in  testing  the  purity  and  po- 
tency of  any  virus,  serum,  toxin,  or  analogous  product. 
Furthermore,  animals  with  the  left  ear  removed  or 
mutilated  so  as  to  prevent  the  detection  of  this  identi- 
fying mark  shall  not  be  used  in  any  test. 

SECTION  7.  Animals  used  in  the  production  or  testing 
of  viruses,  serums,  toxins,  or  analogous  products  shall 
not  be  treated  with  biological  products  other  than  those 
which  are  incidental  to  the  preparation  and  testing  of 
the  products  prepared  from  or  tested  upon  said  animals, 
except  with  the  approval  of  and  in  such  manner  as  may 
be  prescribed  by  the  chief  of  bureau. 


APPENDIX  271 

SECTION  8.  Paragraph  1.  If  for  any  reason  hyper- 
immune  hogs  are  practically  the  only  animals  held  upon 
the  premises  of  a  licensed  establishment,  they  shall  be 
caused  to  range  in  contact  with  calves  in  the  manner 
prescribed  in  section  3  of  this  regulation  for  a  period  of 
at  least  10  days  prior  to  their  being  subjected  to  carotid 
or  final  bleeding. 

Paragraph  2.  All  animals  with  which  hyperimmune 
hogs  have  been  held  in  contact  as  prescribed  in  this  sec- 
tion, shall  be  held  on  the  premises  of  the  licensed  estab- 
lishment and  under  the  observation  of  a  bureau  employee 
for  at  least  two  weeks  after  the  hyperimmune  hogs  have 
been  destroyed. 

Paragraph  3.  All  hyperimmune  hogs  which  are  sub- 
jected to  the  tail-bleeding  process  only,  shall  be  held 
under  the  supervision  of  a  bureau  employee  for  at  least 
two  weeks  after  the  last  tail  bleeding  has  been  col- 
lected. 

SECTION  9.  Paragraph  1.  Establishments  licensed  to 
prepare  hog-cholera  virus  and  anti-hog-cholera  serum 
shall  not  remove  either  hogs  or  calves  from  the  premises 
of  the  establishment  without  written  permission  obtained 
in  advance  from  the  inspector  in  charge. 

Paragraph  2.  Permission  for  the  removal  of  hogs  or 
calves  from  the  premises  of  licensed  establishments  for 
the  purpose  of  immediate  slaughter  shall  be  given  by  the 
inspector  in  charge  under  the  following  conditions : 

(a)  When  such  animals  are  found  not  to  be  affected 
with  any  disease  or  condition  that  may  render  them  in 
whole  or  in  part  unfit  for  food  purposes.  . 

(&)  When  such  animals  are  found  to  be  affected  with 
any  disease  or  condition  which  may  render  them  unfit 
for  food  purposes  in  whole  or  in  part,  provided  said 
animals  are  slaughtered  at  an  establishment  where  Fed- 
eral meat  inspection  is  maintained,  and  provided  fur- 
ther, that  the  inspector  in  charge  of  meat  inspection 


272  HOG    CHOLERA 

where  said  animals  are  to  be  slaughtered  is  given  due 
notice  thereof. 

Paragraph  3.  Permission  for  the  removal  of  hogs  or 
calves  from  the  premises  of  licensed  establishments  for 
purposes  other  than  immediate  slaughter  shall  be  given 
by  the  inspector  in  charge  under  the  following  condi- 
tions: 

(a)  Calves  may  be  removed  if  found  to  be  free  from 
any  infectious,  contagious,  or  communicable  disease, 
provided  the  feet  and  legs  of  calves  used  for  testing 
hog-cholera  virus  or  anti-hog-cholera  serum  are  cleaned 
and  disinfected  with  a  2  per  cent  aqu.eous  solution  of 
cresol  compound,  U.  S.  P.,  or  a  permitted  substitute 
therefor  and  the  animals  held  in  noninfectious  pens  on 
the  premises  of  the  establishment  for  at  least  three  hours 
before  being  loaded  for  transportation. 

(&)  Hogs  which  survive  inoculation  and  exposure  for 
the  production  of  hog-cholera  virus,  surviving  controls 
from  tests  of  anti-hog-cholera  serum,  and  surviving  hogs 
which  have  been  used  for  testing  hog-cholera  virus  may 
be  removed  from  the  premises  of  the  establishment  not 
sooner  than  15  days  subsequent  to  the  day  of  inocula- 
tion and  exposure,  provided  they  are  healthy.  It  is 
required,  however,  that  all  such  hogs  before  their  re- 
moval from  the  premises  be  given  the  serum-alone  treat- 
ment as  prescribed  under  (a)  of  paragraph  4  of  this 
section.  Hyperimmune  hogs  and  pigs  used  for  testing 
the  purity  and  potency  of  anti-hog-cholera  serum  may 
be  removed  from  the  premises  of  licensed  establishments 
21  days  subsequent  to  the  day  of  hyperimmunization  or 
inoculation,  provided  they  exhibit  no  symptoms  of  any 
infectious,  contagious,  or  communicable  disease  and  pro- 
vided further  that  they  are  first  disinfected  as  provided 
in  paragraph  4  of  this  section.  Other  hogs  shall  be 
removed  from  the  premises  of  the  establishment  only 
after  treatment  and  disinfection  as  provided  in  para- 


APPENDIX  273 

graph  4  of  this  section,  except  that  such  hogs  need  not 
be  held  21  days  when  treated  with  serum  and  virus 
which  have  been  released  for  marketing. 

Paragraph  4.  Hogs  which  require  treatment  as  pro- 
vided under  (b)  in  paragraph  3  of  this  section  shall  be 
treated  and  disinfected  as  follows: 

(a)  Serum-alone  method. — The  serum  used  shall  have 
been  prepared  and  released  for  marketing  at  an  estab- 
lishment holding  a  license  from  the  Secretary  of  Agri- 
culture and  the  dose  employed  shall  conform  to  that  re- 
quired in  paragraph  1,  section  6,  or  paragraph  3,  sec- 
tion 10  of  Regulation  19.  After  receiving  this  treatment 
they  shall  be  disinfected  by  dipping  in  a  2  per  cent 
aqueous  solution  of  cresol  compound,  U.  S.  P.,  or  a  per- 
mitted substitute  therefor,  except  when  prevailing  low 
temperatures  make  it  impracticable,  and  be  held  in  non- 
infectious  pens  for  at  least  3  hours  before  being  loaded 
for  transportation. 

(6)  Simultaneous-inoculation  method. —  The  serum 
and  virus  used  shall  have  been  prepared  at  an  establish- 
ment holding  a  license  from  the  Secretary  of  Agriculture 
and  the  doses  shall  be  not  less  than  those  required  in 
paragraph  1,  section  6,  or  paragraph  3,  section  10  of 
Regulation  19.  After  receiving  this  treatment  they  shall 
be  held  under  the  supervision  of  a  bureau  employee  for 
a  period  of  at  least  21  days,  except  when  treated  with 
virus  and  serum  released  for  marketing.  If  no  symp- 
toms of  hog  cholera  or  other  infectious,  contagious,  or 
communicable  disease  are  exhibited  by  the  animals,  they 
shall  be  disinfected  by  dipping  in  a  2  per  cent  aqueous 
solution  of  cresol  compound,  U.  S.  P.,  or  a  permitted 
substitute  therefor,  except  when  prevailing  low  tempera- 
tures make  it  impracticable,  and  held  in  noninfectious 
pens  for  a  period  of  at  least  3  hours  before  being  loaded 
for  transportation. 

SECTION  10.     Except  as  otherwise  provided  in  these 


274  HOG   CHOLERA 

regulations,  all  animals  used  by  licensed  establishments 
in  the  preparation  or  testing  of  veterinary  biologies  shall 
meet  such  requirements  as  may  be  prescribed  by  the 
Chief  of  the  Bureau  of  Animal  Industry  and  deemed  by 
him  necessary  to  prevent  the  preparation  and  sale  of  any 
worthless,  contaminated,  dangerous,  or  harmful  viruses, 
serums,  toxins,  or  analogous  products. 

SECTION  11.  Each  licensed  establishment  shall  adopt 
such  measures  as  the  chief  of  bureau  shall  from  time  to 
time  prescribe  for  carrying  out  the  provisions  of  this 
regulation. 

REGULATION  18. HOG-CHOLERA  VIRUS 

SECTION  1.  Paragraph  1.  All  operations  incident  to 
the  production  of  hog-cholera  virus  shall  be  conducted 
under  the  supervision  of  a  bureau  employee.  Each 
licensed  establishment  shall  notify  the  inspector  in 
charge  or  his  assistant  a  reasonable  time  in  advance  when 
any  operations  are  to  be  conducted. 

Paragraph  2.  Pigs  which  are  used  in  the  production 
of  hog-cholera  virus  shall  be  healthy  and  the  tempera- 
ture of  each  animal  shall  be  accurately  taken  and  per- 
manently recorded  by  the  establishment  immediately  be- 
fore inoculation  when  in  the  opinion  of  the  inspector  in 
charge  this  is  necessary  to  determine  the  health  of  the 
animals.  Each  animal  shall  be  subjected  to  a  careful 
examination  by  a  veterinary  inspector  immediately  prior 
to  inoculation. 

Paragraph  3.  Temperatures  of  all  pigs  used  to  pro- 
duce hog-cholera  virus  shall  be  correctly  taken  and  re- 
corded by  licensed  establishments  each  day  subsequent 
to  the  fifth  day  after  inoculation  and  at  such  other  times 
as  the  inspector  in  charge  may  deem  necessary.  The 
temperature  of  each  pig  invariably  shall  be  taken  and 
recorded  on  each  day  the  animal  is  found  to  be  visibly 
sick. 


APPENDIX  275 

Paragraph  4.  Pigs  which  have  been  inoculated  for 
the  production  of  hog-cholera  virus  shall  be  killed  for 
this  purpose  only  after  a  veterinary  inspector  has  ob- 
served well-marked  symptoms  of  hog  cholera. 

Paragraph  5.  All  pigs  from  which  hog-cholera  virus 
is  derived  shall  be  subjected  to  a  post-mortem  examina- 
tion by  a  veterinary  inspector. 

Paragraph  6.  Hog-cholera  virus  derived  from  pigs 
which  become  visibly  sick  within  three  days  after  the 
time  they  are  admitted  to  the  premises  of  licensed  estab- 
lishments shall  be  destroyed  as  provided  in  section  11, 
Regulation  8,  under  the  supervision  of  a  bureau  em- 
ployee. 

Paragraph  7.  Hog-cholera  virus  derived  from  pigs 
which  upon  post-mortem  examination  do  not  show  le- 
sions of  acute  hog  cholera  or  which  are  found  to  be  so 
affected  with  any  infectious,  contagious,  or  communi- 
cable disease  or  in  such  condition  as  to  render  the  virus 
contaminated,  shall  be  destroyed  as  provided  in  section 
11,  Regulation  8,  under  the  supervision  of  a  bureau 
employee.  A  diagnosis  of  hog  cholera  will  not  be  made 
unless  macroscopic  lesions  of  the  disease  are  found  in 
two  or  more  organs  or  tissues. 

Paragraph  8.  Hog-cholera  virus  derived  from  pigs 
which  are  found  to  be  affected  with  tuberculosis  shall  be 
destroyed  as  provided  in  section  11,  Regulation  8,  under 
the  supervision  of  a  bureau  employee,  unless  the  lesions 
are  slight  or  are  localized,  and  are  calcified  or  encapsu- 
lated. Hog-cholera  virus  derived  from  pigs  so  affected 
may  be  marketed  only  when  the  product  is  heated  as 
provided  in  paragraph  6,  section  3,  of  this  regulation. 

Paragraph  9.  All  records  shall  indicate  clearly  the 
particular  animal,  or  group  of  animals,  from  which  each 
batch  of  hog-cholera  virus  is  derived.  The  amount  col- 
lected and  the  total  amount  after  phenolization  should 
be  separately  recorded. 


276  HOG   CHOLERA 

Paragraph  10.  Hog-cholera  virus  shall  not  be  re- 
moved from  the  premises  of  a  licensed  establishment  un- 
less the  virus  has  been  prepared  in  accordance  with  the 
provisions  of  these  regulations. 

Paragraph  11.  No  immediate  or  true  container  of 
hog-cholera  virus  shall  be  filled  in  whole  or  in  part,  and 
no  trade  label  shall  be  affixed  to  such  containers  except 
under  the  supervision  of  a  bureau  employee. 

Paragraph  12.  The  following  special  facilities,  and 
such  others  as  may  be  required  by  the  chief  of  bureau, 
shall  be  provided  by  each  establishment  licensed  to  pre- 
pare hog-cholera  virus: 

(a)  Separate  operating  rooms. 

(6)  A  separate  room  in  which  the  animals  shall  be 
washed,  cleaned,  and  otherwise  prepared  before  being- 
taken  into  the  operating  room. 

(c)  A  separate  room  for  conducting  autopsies. 

(d)  A  separate  room  for  the  preparation  and  mixing 
of  virus. 

(e)  A   separate    room   for   washing   and   sterilizing 
equipment. 

(/)  Clean  cloths  which  shall  be  kept  damp  when  in 
use,  to  be  used  for  covering  pigs  during  all  operations 
incident  to  the  collection  of  hog-cholera  virus. 

(g)  All  outside  screens,  openings,  and  windows  shall 
be  equipped  with  dust  screens. 

Paragraph  13.  All  persons,  immediately  before  en- 
tering the  operating  or  laboratory  rooms  of  an  establish- 
ment licensed  to  prepare  hog-cholera  virus,  shall  change 
their  outer  clothing  or  cover  it  by  the  use  of  clean 
gowns,  or  other  satisfactory  garments. 

SECTION  2.  Paragraph  1.  For  use  in  the  production 
of  hyperimmunizing  virus,  licensed  establishments  shall 
inoculate  young  pigs  weighing  not  more  than  145  pounds 
each  with  at  least  2  cubic  centimeters  of  a  virulent  strain 
of  hog-cholera  virus. 


APPENDIX  277 

Paragraph  2.  Hyperimmunizing  virus  prepared  in 
accordance  with  sections  1  and  2  of  this  regulation  may 
be  transported  from  one  licensed  establishment  to  an- 
other under  bureau  seal,  provided  the  product  is  prop- 
erly iced  and  its  transfer  is  accomplished  in  such  man- 
ner and  by  such  methods  as  shall  be  approved  by  the 
chief  of  bureau. 

SECTION  3.  Paragraph  1.  For  use  in  the  production 
of  simultaneous  virus,  licensed  establishments  shall  in- 
oculate young  pigs  weighing  not  less  than  40  pounds, 
nor  more  than  100  pounds  each  with  at  least  two 
cubic  centimeters  of  a  virulent  strain  of  hog-cholera 
virus. 

Paragraph  2.  Simultaneous  virus  shall  not  be  col- 
lected from  pigs  which  become  visibly  sick  on  or  before 
the  fourth  day,  or  subsequent  to  the  seventh  day  after 
the  time  of  inoculation.  The  physical  condition  of  pigs 
from  which  simultaneous  virus  is  collected  shall  be  re- 
corded daily  on  and  after  the  fourth  day  subsequent  to 
inoculation. 

Paragraph  3.  Simultaneous  virus  shall  be  collected 
only  from  pigs  which  exhibit  visible  symptoms  of  hog 
cholera  within  seven  days,  and  are  visibly  sick  of  this 
disease  to  a  degree  sufficient  to  result  in  death  within 
15  days  after  the  time  of  inoculation. 

Paragraph  4.  Pigs  which  have  been  inoculated  for 
the  production  of  simultaneous  virus  shall  be  killed  only 
after  permission  has  been  obtained  from  an  authorized 
bureau  employee. 

Paragraph  5.  Simultaneous  virus  shall  be  defibri- 
nated  promptly  after  collection,  and  immediately  there- 
after chilled  and  maintained  at  a  temperature  not  to 
exceed  55°  F.  (12.8°  C.). 

Paragraph  6.  When  simultaneous  virus  is  heated  it 
shall  be  done  under  the  supervision  of  a  bureau  employee 
and  in  such  manner  as  to  subject  the  product  and  the 


278  HOG    CHOLERA 

entire  container  thereof  to  a  temperature  ranging  from 
50°  to  50.5°  C.  for  12  hours. 

Paragraph  7.  Simultaneous  virus  which  has  been 
heated,  as  provided  in  the  preceding  paragraphs,  shall 
not  be  handled  thereafter  in  a  manner  which  will  ex- 
pose the  product  to  contamination. 

Paragraph  8.  When  simultaneous  virus  is  heated,  as 
described  in  paragraph  6  of  this  section,  and  tested  upon 
pigs,  as  hereinafter  provided,  the  product  need  not  be 
tested  upon  calves. 

Paragraph  9.  When  simultaneous  virus  is  heated,  each 
batch  shall  be  tested  for  virulence  by  inoculating  intra- 
muscularly, with  two  cubic  centimeters  of  virus,  each 
of  two  pigs  which  are  susceptible  to  hog  cholera.  Should 
the  pigs  thus  inoculated  exhibit  visible  symptoms  of  hog 
cholera,  as  required  for  pigs  inoculated  to  furnish  simul- 
taneous virus,  the  virus  under  test  may  be  marketed. 

Paragraph  10.  Pigs  selected  for  testing  the  virulence 
of  heated  simultaneous  virus  shall  be  inoculated  imme- 
diately after  their  admission  to  the  premises.  The  quar- 
ters where  these  pigs  are  held  during  the  test  shall  be 
isolated  as  completely  as  feasible  from  quarters  occu- 
pied by  other  pigs  sick  of  hog  cholera.  All  reasonable 
precautions  shall  be  taken  to  prevent  infection  of  these 
pigs  from  sources  other  than  by  inoculation.  Such  pre- 
cautions shall  include  a  thorough  cleaning  and  disinfec- 
tion of  the  pen  in  which  the  pigs  are  held  during  the 
test,  and  a  disinfection  of  these  animals  after  they  are 
placed  in  a  holding  pen.  The  disinfection  of  these  pens 
and  the  test  pigs  shall  be  accomplished  by  such  methods 
as  shall  be  approved  by  the  chief  of  bureau. 

SECTION  4.  Paragraph  1.  Simultaneous  virus  shall  be 
collected  in  batches  of  not  to  exceed  20,000  cubic  centi- 
meters each  and  each  batch  shall  be  mixed  thoroughly  in 
a  single  container. 

Paragraph  2.     After  mixing,  but  before  phenoliza- 


APPENDIX  279 

tion,  a  representative  sample  of  each  batch,  consisting  of 
at  least  15  cubic  centimeters  of  the  mixture,  shall  be 
taken  by  a  bureau  employee.  This  sample  shall  be  known 
as  the  "Virus-test  sample. " 

Paragraph  3.  Simultaneous  virus  which  has  been 
mixed  as  provided  in  this  section,  after  withdrawal  of 
the  "Virus-test  sample,"  shall  have  added  to  it  a  suffi- 
cient quantity  of  a  5  per  cent  solution  of  phenol  so  that 
the  virus  will  contain  one-half  of  1  per  cent  phenol  by 
volume.  This  phenolization  must  be  accomplished  with 
accuracy  and  in  a  manner  which  will  prevent  undesir- 
able changes  in  the  product.  After  thorough  mixing  in  a 
single  container,  a  representative  sample,  consisting  of 
at  least  100  cubic  centimeters,  collected  in  three  contain- 
ers, shall  be  taken  by  a  bureau  employee.  This  sample 
shall  be  known  as  the  "Virus-stock  sample. " 

Paragraph  4.  Simultaneous  virus  which  has  been 
mixed  and  phenolized,  as  provided  in  this  section,  to- 
gether with  the  virus-stock  sample  and  the  unused  resi- 
due of  the  virus-test  sample,  shall  be  placed  under  bu- 
reau lock  and  held  as  provided  under  (&),  section  1  of 
Regulation  7  until  such  time  as  the  tests  have  shown 
the  batch  of  virus  to  be  virulent  and  free  from  contami- 
nation. 

Paragraph  5.  At  least  one  container  of  the  virus-stock 
sample  shall  be  held  unopened  under  bureau  lock,  in  the 
manner  provided  in  Regulation  7,  for  at  least  three 
months  after  the  expiration  of  the  latest  return  date 
shown  upon  the  trade  labels  affixed  to  the  immediate  or 
true  containers  of  the  product  corresponding  to  the 
virus-stock  sample.  Unless  the  virus  is  heated  as  pro- 
vided in  paragraph  6,  section  3,  of  this  regulation  the 
virus-test  sample  described  in  paragraph  2  of  this  sec- 
tion shall  be  used  to  determine  the  freedom  from  con- 
tamination of  each  batch  of  simultaneous  virus. 

Paragraph  6.    Two  healthy  calves,  with  mouths  free 


280  HOG   CHOLERA 

from  abrasions,  and  not  less  than  3  nor  more  than  12 
months  old,  shall  be  furnished  by  the  establishment  for 
the  inoculation  with  the  virus-test  sample. 

Paragraph  7.  All  animals  used  for  the  testing  of 
simultaneous  virus  shall  be  inoculated  only  under  the 
supervision  of  a  veterinary  inspector,  and  shall  be 
marked  as  provided  in  paragraphs  2,  3,  4,  and  5,  section 
6  of  Kegulation  17. 

Paragraph  8.  Each  of  the  calves  selected  for  testing 
the  purity  of  simultaneous  virus  shall  be  inoculated  by 
injecting  5  cubic  centimeters  of  the  virus-test  sample 
into  either  the  auricular  or  jugular  vein  within  24  hours 
after  the  virus  is  collected. 

Paragraph  9.  Calves  inoculated  for  the  purpose  of 
determining  the  purity  of  simultaneous  virus  as  pro- 
vided in  the  preceding  paragraph  shall  be  held  under 
the  observation  of  a  veterinary  inspector  for  a  period  of 
at  least  7  days.  Should  foot-and-mouth  disease  appear 
in  the  United  States  the  said  calves  shall  be  held  under 
the  observation  of  a  veterinary  inspector  for  10  days 
or  longer,  in  the  discretion  of  the  inspector  in  charge. 

Paragraph  10.  Simultaneous  virus  which  has  been 
either  heated,  as  provided  in  paragraph  6,  section  3  of 
this  regulation,  or  subjected  to  the  test  prescribed  in 
paragraph  8,  section  4  of  this  regulation,  may  be  re- 
leased for  marketing,  provided  the  animals  treated  with 
the  virus  remain  well  and  develop  no  symptoms  of  any 
infectious,  contagious,  or  communicable  disease. 

Paragraph  11.  Simultaneous  virus  found  to  be  worth- 
less or  contaminated  shall  be  destroyed  as  provided  in 
section  11,  Regulation  8,  under  the  supervision  of  a 
bureau  employee. 

SECTION  5.  Paragraph  1.  Each  immediate  or  true 
container  of  simultaneous  virus  which  has  been  tested 
and  found  not  to  be  worthless  or  contaminated  shall  bear 
a^stamp  or  mark  approved  by  the  department.  Such 


APPENDIX  281 

stamp  or  mark  shall  bear  the  phrase  "U.  S.  Released." 
Each  container  of  simultaneous  virus  shall  be  appropri- 
ately sealed  with  a  suitable  material  and  the  aforesaid 
stamp  or  mark  securely  affixed  to  the  sealing  material 
under  the  supervision  of  a  bureau  employee.  Should 
any  difficulty  result  from  the  action  of  moisture  upon 
said  stamp  or  mark,  causing  it  to  become  detached  or 
illegible,  that  portion  of  the  container  which  has  been 
sealed  and  stamped  shall  be  subjected  at  once  to  dipping 
in  hot  paraffin  or  other  waterproof  material. 

Paragraph  2.  The  trade  label  on  each  immediate  or 
true  container  of  simultaneous  virus  shall  bear  the  date 
of  manufacture,  which  date  shall  be  the  day  on  which 
the  virus  is  collected. 

Paragraph  3.  The  return  date  placed  upon  the  label 
of  each  immediate  or  true  container  of  simultaneous 
virus  shall  be  a  date  within  60  days  after  the  date  of 
manufacture. 

Paragraph  4.  Trade  labels  affixed  to  or  used  in  con- 
nection with  the  immediate  or  true  containers  of  hog- 
cholera  virus  shall  plainly  show  the  amount  of  the  con- 
tents of  said  containers. 

Paragraph  5.  Trade  labels  affixed  to  or  used  in  con- 
nection with  each  immediate  or  true  container  of  simul- 
taneous virus  shall  bear  a  dosage  table  in  which  the  doses 
recommended  are  not  less  than  those  appearing  in  the 
following  table: 

Weight.  Minimum  dose. 

Pigs  weighing  100  pounds  or  less 1  c.  c. 

Hogs  weighing  more  than  100  pounds. . .  2  c.  c. 

Paragraph  6.  No  hog-cholera  virus  shall  be  released 
for  marketing  unless  and  until  all  information  required 
by  these  regulations  has  been  affixed  to  the  containers 
thereof  under  the  supervision  of  a  bureau  employee. 


282  HOG    CHOLERA 

REGULATION   19. — ANTI-HOG-CHOLERA   SERUM 

SECTION  1.  All  operations  incident  to  the  production 
of  anti-hog-cholera  serum  shall  be  conducted  under  the 
supervision  of  a  bureau  employee.  Each  licensed  estab- 
lishment shall  notify  the  inspector  in  charge,  or  an  as- 
sistant, a  reasonable  time  in  advance  when  any  opera- 
tions are  to  be  conducted. 

SECTION  2.  Paragraph  1.  Anti-hog-cholera  serum 
shall  be  derived  only  from'  hyperimmune  hogs  which 
have  been  immune  to  hog  cholera  for  at  least  60  days 
prior  to  hyperimmunization. 

Paragraph  2.  Anti-hog-cholera  serum  shall  be  derived 
only  from  hyperimmune  hogs  which  have  been  subjected 
to  not  more  than  4  successive  bleedings  after  each  hyper- 
immunization.  The  first  bleeding  shall  take  place  not 
earlier  than  10  days  after  hyperimmunization,  subse- 
quent bleedings  shall  not  take  place  more  frequently 
than  once  in  7  days,  and  the  last  bleeding  shall  be  made 
on  a  date  not  later  than  38  days  after  hyperimmuniza- 
tion. 

Paragraph  3.  Hogs  which  are  used  to  produce  anti- 
hog-cholera  serum  shall  be  healthy  at  the  time  of  hyper- 
immunization, this  fact  to  be  determined  by  a  careful 
examination  made  by  a  veterinary  inspector  prior  to 
hyperimmunization.  The  temperature  and  weight  of 
each  animal  shall  be  accurately  obtained  and  recorded 
by  the  establishment  before  hyperimmunization. 

Paragraph  4.  All  hogs  which  are  used  to  produce 
anti-hog-cholera  serum  shall  receive  a  single  intravenous 
injection  of  at  least  5  cubic  centimeters  of  hog-cholera 
virus  for  each  pound  of  the  animal's  weight. 

Paragraph  5.  Temperature  of  all  hogs  used  to  pro- 
duce anti-hog-cholera  serum  shall  be  accurately  taken 
and  recorded  by  licensed  establishments,  either  on  the 
afternoon  before  or  on  the  day  of  bleeding,  and  at  such 


APPENDIX  283 

other  times  as  the  inspector  in  charge  may  deem  neces- 
sary. All  temperatures  shall  be  taken  under  normal 
conditions  so  far  as  possible  and  in  a  manner  which  will 
expedite  the  work. 

Paragraph  6.  All  hogs  which  are  used  to  produce 
anti-hog-cholera  serum  shall  be  subjected  to  a  careful 
examination  by  a  veterinary  inspector  immediately  prior 
to  each  bleeding.  Only  those  hogs  shall  be  bled  for 
serum  which  are  found  to  have  a  temperature  of  less 
than  104°  F.  and  are  free  from  infectious,  contagious, 
or  communicable  diseases  or  other  harmful  conditions. 

Paragraph  7.  All  hogs  from  which  anti-hog-cholera 
serum  is  derived  shall  be  subjected  to  a  post-mortem  ex- 
amination by  a  veterinary  inspector,  except  as  herein- 
after provided,  and  if,  as  a  result  of  such  examination, 
it  is  found  that  any  hog  is  so  affected  with  any  infec- 
tious, contagious,  or  communicable  disease,  or  is  in  such 
condition  as  to  render  the  serum  worthless,  contami- 
nated, dangerous,  or  harmful,  the  serum  collected  from 
such  hogs  shall  be  destroyed  by  the  establishment  as  pro- 
vided in  section  11,  Regulation  8,  under  the  supervision 
of  a  bureau  employee.  Serum  derived  from  hogs  which 
are  found  to  be  affected  with  tuberculosis  need  not  be 
destroyed,  provided  the  lesions  are  slight  or  are  localized, 
and  are  calcined  or  encapsulated. 

Paragraph  8.  Anti-hog-cholera  serum  derived  from 
each  hyperimmune  hog  shall  be  kept  separate  and  apart 
from  other  serum  except  when  heated  as  prescribed  in 
paragraph  10  of  this  section,  until  it  has  been  determined 
by  post-mortem  examination  that  the  hog  from  which 
the  serum  is  derived  is  not  so  affected  with  any  infec- 
tious, contagious,  or  communicable  disease  or  is  in  such 
condition  as  to  render  the  serum  worthless,  contami- 
nated, dangerous,  or  harmful. 

Paragraph  9.  When  anti-hog-cholera  serum  is  heated 
as  described  in  the  following  paragraph,  the  serum  de- 


284  HOG   CHOLEKA 

rived  from  each  hyperimmune  hog  may  be  appropriately 
mixed  with  serum  from  other  hyperimmune  hogs  imme- 
diately after  collection,  provided  the  final  batch  or  mix- 
ture is  prepared  as  prescribed  in  the  following  para- 
graphs of  this  section. 

Paragraph  10.  Heating  of  anti-hog-cholera  serum 
shall  be  conducted  under  the  supervision  of  a  bureau 
employee  and  in  a  manner  in  which  the  product  and  the 
entire  container  thereof  will  be  subjected  to  a  tempera- 
ture ranging  from  59°  to  60°  C.  for  30  minutes. 

Paragraph  11.  Anti-hog-cholera  serum  which  has 
been  heated  as  provided  in  the  preceding  paragraph 
shall  not  be  handled  thereafter  in  a  manner  which  will 
expose  the  product  to  contamination.  Final  mixtures  or 
batches  of  anti-hog-cholera  serum  shall  contain  relative 
proportions  of  the  several  bleedings.  Single  bleedings 
from  each  hog  shall  not  be  divided  or  become  a  part  of 
two  or  more  batches  unless  the  serum  is  subjected  to 
heat  as  described  in  paragraph  10  of  this  section. 

Paragraph  12.  Anti-hog-cholera  serum  which  is  to 
constitute  a  batch  or  portion  thereof  may  be  strained 
into  a  single  container,  after  which  the  amount  should 
be  accurately  determined. 

Paragraph  13.  Anti-hog-cholera  serum  shall  have 
added  thereto  a  sufficient  quantity  of  a  5  per  cent  solu- 
tion of  phenol  to  make  the  serum  contain  one-half  of  1 
per  cent  of  phenol  by  volume. 

Paragraph  14.  Phenolization  of  anti-hog-cholera  se- 
rum must  be  accomplished  with  accuracy,  and  in  a  man- 
ner which  will  prevent  the  occurrence  of  undesirable 
changes  in  the  product. 

Paragraph  15.  All  records  shall  indicate  clearly  the 
particular  hog  or  group  of  hogs  from  which  each  batch 
of  serum  or  portion  thereof  is  derived.  The  amount 
prepared  for  phenolization  and  the  total  amount  after 
phenolization  shall  be  separately  recorded. 


APPENDIX  285 

SECTION  3.  Paragraph  1.  Anti-hog-cholera  serum 
prior  to  testing  shall  be  collected  in  batches  of  not  more 
than  100,000  cubic  centimeters  each,  which  shall  be 
thoroughly  mixed  in  a  single  container.  After  mixing 
and  phenolizing,  a  representative  sample  consisting  of 
at  least  375  cubic  centimeters  collected  in  three  contain- 
ers of  not  less  than  25  centimeters,  each  to  be  known  as 
the  "Serum-test  sample,"  shall  be  taken  and  marked 
with  identifying  marks  by  a  bureau  employee.  The  se- 
rum, together  with  the  test  sample,  shall  be  placed  under 
bureau  lock,  as  provided  under  (b)  section  1,  Regula- 
tion 7,  and  so  held  until  such  time  as  the  tests  required 
by  these  regulations  have  been  completed,  and  have 
shown  that  the  serum  is  not  worthless,  contaminated, 
dangerous,  or  harmful. 

Paragraph  2.  If  the  serum  is  released,  one  of  the 
three  containers  of  the  test  sample  thereof  shall  be.  held 
under  bureau  lock  for  at  least  six  months  after  the  latest 
return  date  shown  on  the  trade  labels  affixed  to  the  im- 
mediate or  true  containers  of  the  serum  of  which  the  test 
sample  is  a  part. 

SECTION  4.  Paragraph  1.  All  anti-hog-cholera  serum 
shall  be  tested  for  purity  and  potency  by  licensed  estab- 
lishments as  prescribed  by  these  regulations. 

Paragraph  2.  For  use  in  testing  each  batch  of  100,- 
000  cubic  centimeters  of  anti-hog-cholera  serum  of  less, 
7  healthy  pigs,  susceptible  to  hog  cholera  and  weighing 
not  less  than  45  pounds  and  not  more  than  90  pounds 
each,  shall  be  furnished  by  the  establishment. 

Paragraph  3.  Each  of  the  seven  pigs  furnished  for 
the  test  shall  be  injected  with  2  cubic  centimeters  of 
hog-cholera  virus;  of  these  pigs  5  shall  receive  20  cubic 
centimeters  of  the  serum  which  is  to  be  tested.  Two  of 
the  pigs  shall  receive  no  serum  and  shall  serve  as  con- 
trols. The  virus  and  serum  injections  shall  be  made 
simultaneously,  the  virus  being  injected  into  the  left  and 


286  HOG   CHOLERA 

the  serum  into  the  right  axillary  space.  The  same  virus 
shall  be  used  for  the  inoculation  of  all  pigs  in  the  test 
and  shall  be  administered  by  a  veterinary  inspector. 

Paragraph  4.  A  veterinary  inspector  shall  indicate 
the  pigs  which  shall  receive  serum  with  virus  and  those 
which  shall  receive  the  virus  only  in  each  serum  test. 

Paragraph  5.  Pigs  which  are  injected  with  serum  in 
serum  tests  shall  be  held  under  the  observation  of  a 
veterinary  inspector  for  a  period  of  21  days,  or  as  much 
longer  as  the  inspector  in  charge  may  deem  necessary 
to  determine  the  health  of  the  animals  and  the  purity 
and  potency  of  the  serum  under  test. 

Paragraph  6.  Pigs  in  serum  tests  which  receive  virus 
only  shall  be  held  under  the  observation  of  a  veterinary 
inspector  and  shall  not  be  removed  from  the  test  unless 
and  until  released  by  such  an  inspector  who  will  permit 
their  removal  when  exhibiting  well-marked  symptoms  of 
hog  cholera,  as  described  in  rule  D,  paragraph  2,  sec- 
tion 5,  of  this  regulation,  or  after  they  have  served  their 
purpose  in  the  tests. 

Paragraph  7.  The  temperature  of  each  pig  used  in  a 
test  of  anti-hog-cholera  serum  shall  be  taken  and  re- 
corded shortly  before  each  test  is  inaugurated. 

Paragraph  8.  Temperatures  of  control  pigs  and  sick 
serum-treated  pigs  in  serum  tests  shall  be  procured  daily 
throughout  the  test  period,  with  the  possible  exception  of 
Sundays  and  holidays,  and  an  accurate  report  of  these 
temperatures  rendered  by  the  establishment  to  the  in- 
spector in  charge  as  he  may  direct. 

Paragraph  9.  When  serum-treated  pigs  do  not  ex- 
hibit symptoms  of  sickness  their  temperatures  need  not 
be  taken  except  when  required  by  the  inspector  in  charge 
or  his  assistants  to  determine  more  accurately  the  true 
physical  condition  of  the  animals  under  observation. 

SECTION  5.     Paragraph  1.     The  following  principle 


APPENDIX  287 

and  rules  are  declared  for  a  guide  in  judging  the  re- 
sults of  serum  tests : 

Principle :  It  is  practically  impossible  in  many  cases 
accurately  to  differentiate  between  hog  cholera,  pneu- 
monia, and  other  conditions  affecting  hogs,  without  the 
aid  of  an  autopsy  as  well  as  applied  laboratory  technique 
and  certain  experiments  which  may  be  necessary  to  de- 
termine the  causative  agent  responsible  for  the  condi- 
tion. Therefore,  when  healthy  pigs  are  selected  for  test- 
ing anti-hog-cholera  serum  any  abnormal  condition 
which  may  arise  in  the  pigs  subsequent  to  their  inocula- 
tion should  be  regarded  as  due  either  to  the  virus  used 
or,  in  the  case  of  the  serum-treated  pigs,  to  the  fact  that 
the  serum  does  not  protect,  unless  the  condition  is  defi- 
nitely known  or  can  be  shown  to  be  due  to  some  other 
cause. 

Paragraph  2.  The  following  rules  shall  be  observed  in 
disposing  of  anti-hog-cholera  serum  which  has  been  sub- 
jected to  the  tests  prescribed  by  this  order: 

Rule  A.  A  serum  test  shall  be  declared  a  "No  test" 
if  any  one  of  the  following  conditions  obtains : 

1.  When  any  of  the  serum-treated  test  pigs  or  both  of 
the  control  pigs  become  visibly  sick  on  or  before  the 
fourth  day  after  the  time  of  inoculation. 

2.  When  both  of  the  control  pigs  do  not  exhibit  symp- 
toms of  hog  cholera  at  some  time  during  the  test  period 
as  described  in  rule  D  of  this  paragraph. 

3.  When  neither  of  the  control  pigs  exhibits  symp- 
toms of  hog  cholera  subsequent  to  the  fourth  day  and 
within  7  days  after  the  time  of  inoculation  as  described 
in  rule  D  of  this  paragraph. 

4.  When  one  or  both  of  the  control  pigs  exhibit  symp- 
toms of  hog  cholera  within  7  days,  as  prescribed  in  rule 
D  of  this  paragraph,  but  do  not  become  sick  to  a  degree 
sufficient  to  result  in  death  within  15  days  after  the 
time  of  inoculation. 


288  HOG   CHOLERA 

5.  When  the  serum-treated  test  pigs  develop  during 
the  test  period  symptoms  of  any  infectious,  contagious, 
or  communicable  disease  (other  than  hog  cholera)  which 
is  not  caused  by  the  serum  used. 

6.  When  a  condition  obtains  in  any  of  the  test  pigs 
which  is  not  otherwise  covered  in  this  section. 

Rule  B.  A  serum  test  shall  be  declared  "unsatisfac- 
tory and  the  serum  contaminated"  when  the  following 
condition  obtains: 

1.  When  during  the  test  period  any  of  the  serum- 
treated  test  pigs  develop  symptoms  of  any  infectious, 
contagious,  or  communicable  disease  (other  than  hog 
cholera)  which  is  due  to  the  serum  used. 

Rule  C.  A  serum  test  shall  be  declared  "Unsatisfac- 
tory ' '  when  any  one  of  the  following  conditions  obtains : 

1.  When  both  of  the  control  pigs  react  as  described  in 
rule  D  of  this  paragraph  and  one  of  the  serum-treated 
pigs  becomes  visibly  sick  subsequent  to  the  fourth  day 
after  the  time  of  inoculation  and  is  found  not  to  have 
fully  recovered  before  the  test  animals  are  released  by  a 
veterinary  inspector,  as  provided  in  paragraph  5,  section 
4,  of  this  regulation. 

2.  When  both  of  the  control  pigs  react  as  described  in 
rule  D  and  two  or  more  of  the  serum-treated  pigs  be- 
come visibly  sick  after  the  fourth  day  after  the  time  of 
inoculation. 

3.  When  an  abscess,  which  is  not  definitely  known  to 
be  due  to  a  cause  other  than  the  serum  used,  develops  at 
the  site  of  the  serum  inoculations  in  any  of  the  serum- 
treated  pigs. 

Rule  D.  A  serum  test  shall  be  declared  "Satisfac- 
tory" when  the  following  conditions  obtain: 

1.  When  both  of  the  control  pigs  exhibit  visible  symp- 
toms of  hog  cholera  at  some  time  during  the  test  period, 
one  of  which  becomes  visibly  sick  of  this  disease  subse- 
quent to  the  fourth  day  of  this  period  but  within  seven 


APPENDIX  289 

days  after  the  test  is  inaugurated,  and  is  sick  to  a  de- 
gree sufficient  to  result  in  death  within  15  days  after  the 
time  of  inoculation,  while  all  of  the  serum-treated  pigs 
remain  well  throughout  the  test  or  not  more  than  one 
of  these  serum-treated  pigs  become  visibly  sick  subse- 
quent to  the  fourth  day  after  the  time  of  inoculation, 
and  fully  recovers  before  the  test  animals  are  released 
by  a  veterinary  inspector  as  provided  in  paragraph  5 
section  4,  of  this  regulation. 

SECTION  6.  Paragraph  1.  Anti-hog-cholera  serum 
may  be  released  for  marketing  as  hereinafter  prescribed 
when  the  test  required  by  this  regulation  is  found  to  be 
satisfactory  as  defined  in  rule  D,  provided  the  product 
is  recommended  for  use  in  doses  not  less  than  those  ap- 
pearing in  the  following  table.  This  table  shall  be  a 
part  of  trade  labels,  wrappers,  and  the  like,  affixed  to  or 
used  in  connection  with  each  immediate  or  true  con- 
tainer of  the  product. 

Weight.  Minimum'  Dose. 

Sucking  pigs   20  c.  c. 

Pigs  20  to  40  pounds   30  c.  c. 

Pigs  40  to  90  pounds   35  c.  c. 

Pigs  90  to  120  pounds    45  c.  c. 

Hogs  120  to  150  pounds 55  c.  c. 

Hogs  150  to  180  pounds 65  c.  c 

Hogs  180  pounds  and  over 75  c.  c. 

Paragraph  2.  Anti-hog-cholera  serum,  the  test  of 
which  has  proved  it  to  be  "Unsatisfactory,"  as  defined 
in  rule  C  of  this  order,  may  be  tested  again  as  described 
in  sections  4  and  5  of  this  regulation.  Should  the  sec- 
ond test  prove  to  be  "Satisfactory,"  as  defined  in  rule 
D,  the  serum  may  be  released  for  marketing  under  the 
conditions  set  forth  in  paragraph  1  of  this  section.  If 
the  test  is  again  found  "Unsatisfactory,"  as  defined  in 
1  and  2,  rule  C,  paragraph  2,  section  5,  of  this  regula- 
tion, the  serum  shall  not  be  marketed  unless  and  until 


290  HOG   CHOLEEA 

it  is  either  concentrated,  refined  and  tested  in  a  manner 
approved  by  the  chief  of  bureau,  or  mixed  with  other 
serum  and  tested  as  provided  in  section  7  of  this  regu- 
lation. 

SECTION  7.  Paragraph  1.  When  it  is  desired  to  mar- 
ket anti-hog-cholera  serum  without  concentration  and  re- 
finement which  has  been  tested  with  the  results  indi- 
cated in  paragraph  2,  section  6,  of  this  regulation,  it 
shall  be  mixed  with  other  anti-hog-cholera  serum  with 
the  view  of  increasing  its  potency  and  the  final  mixture 
shall  consist  of  not  less  than  50  per  cent  nor  more  than 
60  per  cent  of  the  serum  of  doubtful  potency. 

Paragraph  2.  Anti-hog-cholera  serum  which  has  been 
mixed  as  provided  in  the  preceding  paragraph  shall  be 
tested  as  outlined  in  sections  4  and  5  of  this  regulation, 
with  the  following  exceptions: 

(a)  Eleven  pigs  in  lieu  of  the  7  shall  be  used,  3  of 
which  shall  receive  virus  only  and  shall  serve  as  controls. 

(&)  Unless  two  of  the  control  pigs  exhibit  visible 
symptoms  of  hog  cholera  subsequent  to  the  fourth  day 
of  the  test  period,  but  within  7  days  after  the  test  is 
inaugurated  and  are  sick  of  this  disease  to  a  degree  suffi- 
cient to  result  in  death  within  15  days  after  the  time 
of  inoculation,  "No  test"  will  be  declared. 

Paragraph  3.  A  second  test  conducted  in  the  same 
manner  as  before  may  be  made  of  serum  mixed  as  pro- 
vided in  paragraph  1  of  this  section  should  the  results  of 
the  test  of  the  mixture  be  declared  "Unsatisfactory"  as 
to  potency. 

SECTION  8.  Paragraph  1.  Should  abscesses  develop 
at  the  sites  of  the  serum  inoculations  in  any  of  the  pigs 
used  for  testing  serum  as  provided  in  this  regulation, 
the  following  rules  shall  apply : 

(a)  Judgment  of  the  results  of  tests  made  on  pigs  to 
determine  the  potency  of  anti-hog-cholera  serum  will  be 


APPENDIX  291 

rendered  irrespective  of  those  conditions  found  which 
are  regarded  as  an  index  to  the  purity  of  the  product. 

(6)  Should  the  results  of  a  test  of  an ti -hog-cholera 
serum  be  declared  "Satisfactory  for  purity,"  and  it  is 
found  necessary  to  subject  the  batch  of  serum  to  a  re- 
test  to  determine  its  potency,  judgment  concerning 
the  purity  of  the  product  shall  be  based  upon  the 
first  test  unless  evidence  is  found  subsequent  to  such 
test  which  indicates  that  the  serum  is  in  fact  contami- 
nated. 

(c)  Should  the  results  of  a  test  of  anti-hog-cholera 
serum  be  declared  ' '  Satisfactory  for  potency ' '  but ' '  Un- 
satisfactory for  purity"  the  product  may  again  be  tested 
for  purity  upon  the  same  number  of  pigs  as  provided 
under  (a),  paragraph  2,  section  7,  of  this  regulation 
provided  each  pig  receives  a  single  injection,  in  the 
axillary  space,  of  at  least  25  cubic  centimeters  of  the 
product  to  be  tested.  Immune  pigs  may  be  used  for  this 
test  if  desired,  and  they  shall  be  held  under  the  super- 
vision of  a  bureau  employee  for  at  least  15  days. 

Paragraph  2.  Anti-hog-cholera  serum  may  be  released 
for  marketing  as  prescribed  in  paragraph  1,  section  6, 
of  this  regulation,  after  having  been  tested,  as  provided 
by  sections  7  and  8  and  found  satisfactory  for  purity 
and  potency. 

SECTION  9.  Paragraph  1.  Anti-hog-cholera  serum 
which  has  been  tested  twice  with  unsatisfactory  results 
as  to  purity  as  provided  in  3  of  rule  C  of  this  regulation 
but  satisfactory  as  to  potency  may  again  be  tested  with 
the  view  of  ascertaining  whether  it  is  in  fact  contami- 
nated with  pus-producing  organisms,  by  treating  50 
hogs  on  the  premises  of  the  manufacturing  establish- 
ment. The  serum  shall  be  administered  under  the  super- 
vision of  a  bureau  employee,  and  each  hog  treated  shall 
receive  a  single  injection,  in  the  axillary  space,  of  not 


292  HOG   CHOLERA 

less  than  25  cubic  centimeters  of  the  product  to  be 
tested. 

Paragraph  2.  Animals  used  for  testing  serum  as  pre- 
scribed in  paragraph  1  of  this  section  shall  be  held  under 
the  supervision  of  a  bureau  employee  for  at  least  15 
days,  and  each  animal  carefully  examined  at  the  sites 
of  the  inoculations  to  determine  whether  or  not  the 
product  has  caused  abscess  formation.  At  the  conclu- 
sion of  the  test  a  report  shall  be  submitted  to  the  Wash- 
ington office  by  letter  concerning  the  results  thereof, 
after  which  the  bureau  will  advise  the  inspector  in 
charge  as  to  what  disposition  should  be  made  of  the 
serum. 

SECTION  10.  Paragraph  1.  Blood  derived  from  hyper- 
immune  hogs  and  ordinary  defibrinated  blood  anti-hog- 
cholera  serum  may  be  clarified,  or  refined  and  concen- 
trated by  licensed  establishments,  provided  methods  used 
to  accomplish  this  are  approved  by  the  chief  of  bureau. 

Paragraph  2.  When  products  described  in  the  pre- 
ceding paragraph  which  have  not  been  tested  or  have 
been  tested  and  found  "  Satisfactory "  are  clarified,  or 
refined  and  concentrated  so  that  the  volume  thereof  is 
reduced  20  per  cent  or  more,  and  it  is  desired  to  market 
the  product  in  doses  smaller  than  those  indicated  in 
paragraph  1,  section  6  of  this  regulation,  it  shall  be 
tested  as  provided  in  sections  4  and  5  of  this  regulation, 
except  that  each  pig  in  the  test  shall  receive  15  cubic 
centimeters  of  the  product  to  be  tested. 

Paragraph  3.  Should  the  test  required  in  paragraph 
2  of  this  section  be  found  "Satisfactory,"  as  provided 
in  rule  D,  paragraph  2,  section  5  of  this  regulation,  the 
product  may  be  marketed,  if  it  is  recommended  for  use 
in  doses  not  less  than  those  appearing  in  the  following 
table.  This  table  shall  be  a  part  of  trade  labels,  wrap- 
pers, and  the  like,  affixed  to  or  used  in  connection  with 
each  immediate  or  true  container  of  the  product: 


APPENDIX  293 

Weight.  Minimum  Dose. 

Sucking  pigs  35  c.  c. 

Pigs  20  to  40  pounds   25  c.  c. 

Pigs  40  to  90  pounds    30  c.  c. 

Pigs  90  to  120  pounds    35  c.  e. 

Hogs  120  to  150  pounds    45  c.  c. 

Hogs  150  to  180  pounds 50  c.  c. 

Hogs  180  pounds  and  over 60  c.  c. 

SECTION  11.  Paragraph  1.  Each  immediate  or  true 
container  of  anti-hog-cholera  serum  which  has  been 
tested  and  found  not  to  be  worthless,  contaminated,  dan- 
gerous, or  harmful  shall  bear  a  stamp  or  mark  approved 
by  this  department.  Such  stamp  or  mark  shall  bear  the 
phrase  "U.  S.  Released."  Each  container  of  anti-hog- 
cholera  serum  shall  be  appropriately  sealed  with  a  suit- 
able material  and  the  aforesaid  stamp  or  mark  shall  be 
affixed  securely  to  the  sealing  material  under  the  super- 
vision of  a  bureau  employee.  Should  any  difficulty  re- 
sult from  the  action  of  moisture  upon  said  stamp  or 
mark  causing  it  to  become  detached  or  illegible,  that  por- 
tion of  the  container  which  has  been  sealed  and  stamped 
shall  be  subjected  at  once  to  dipping  in  hot  paraffin  or 
other  waterproof  material. 

Paragraph  2.  The  return  date  placed  upon  trade 
labels  of  anti-hog-cholera  serum  shall  be  a  date  not  more 
than  two  years  after  the  date  of  bleeding.  The  date  of 
bleeding  shall  be  regarded  as  the  date  upon  which  the 
first  serum  was  collected,  which  is  a  part  of  the  batch. 

Paragraph  3.  Should  the  return  date  of  any  batch 
of  anti-hog-cholera  serum  which  has  been  tested  as  pro- 
vided in  this  regulation  expire  before  the  serum  is  used, 
this  date  may  be  extended  one  year,  provided  the  serum 
is  retested  and  found  satisfactory  as  defined  in  rule  D, 
paragraph  2,  section  5,  of  this  regulation. 

Paragraph  4.  Trade  labels  affixed  to  or  used  in  con- 
nection with  the  immediate  or  true  containers  of  anti- 


294  HOG    CHOLERA 

hog-cholera  serum  shall  plainly  show  the  quantity  of 
the  contents  of  said  containers. 

Paragraph  5.  No  immediate  or  true  container  of  anti- 
hog-cholera  serum  shall  be  filled  in  whole  or  in  part,  and 
no  trade  label  shall  be  affixed  to  such  containers,  except 
under  the  supervision  of  a  bureau  employee. 

Paragraph  6.  Anti-hog-cholera  serum  shall  not  be 
removed  from  the  premises  of  a  licensed  establishment 
unless  it  has  been  prepared  in  accordance  with  the  pro- 
visions of  these  regulations. 

Paragraph  7.  No  anti-hog-cholera  serum  shall  be  re- 
leased for  marketing  unless  and  until  all  of  the  informa- 
tion required  by  those  regulations  has  been  affixed  to 
the  containers  thereof  under  the  supervision  of  a  bureau 
employee. 

SECTION  12.  The  following  special  facilities  and  such 
others  as  may  be  required  by  the  chief  of  bureau  shall 
be  provided  by  each  establishment  licensed  to  prepare 
anti-hog-cholera  serum. 

(a)  Separate  operating  rooms. 

(&)  A  separate  room  in  which  the  hogs  shall  be 
washed,  cleaned,  and  otherwise  prepared  before  being 
taken  into  the  operating  room. 

(c)  A  separate  room  for  conducting  autopsies. 

(d)  A  separate  room  for  the  preparation  and  mixing 
of  serum. 

(e)  A   separate    room    for   washing   and    sterilizing 
equipment. 

(/)  Clean  cloths,  which  shall  be  kept  damp  when  in 
use,  to  be  used  for  covering  hogs  during  all  operations 
incident  to  the  collection  of  anti-hog-cholera  serum. 

(g)  All  outside  doors,  windows,  or  other  openings 
shall  be  equipped  with  dust  screens. 

SECTION  13.  All  persons  immediately  before  entering 
the  operating  or  laboratory  rooms  of  an  establishment, 
licensed  to  prepare  anti-hog-cholera  serum,  shall  change 


APPENDIX  295 

their  outer  clothing  or  effectively  cover  the  same  by  the 
use  of  gowns  or  other  satisfactory  garments. 


REGULATION   20. — BACTEBINS,    VACCINES,    TOXINS,   ETC. 

SECTION  1.  Paragraph  1.  Viruses  entering  into  the 
preparation  of  bacterins,  vaccines,  or  toxins  shall  be  de- 
rived from  animals  which  are  affected  with  no  disease 
other  than  that  for  which  the  bacterins,  vaccines,  or 
toxins  are  intended  to  be  used. 

Paragraph  2.  All  bacterins,  vaccines,  and  toxins,  shall 
be  derived  from  the  specific  cause  of  the  diseases  for 
which  they  are  intended  to  be  used,  or  from  the  secon- 
dary invaders  of  the  respective  diseases. 

SECTION  2.  Paragraph  1.  The  return  date  on  the 
trade  labels  of  blackleg  vaccine  prepared  from  attenu- 
ated B.  gangrcence  emphysematosce  or  blackleg  muscle 
virus,  shall  be  a  date  not  more  than  6  months  later  than 
the  date  on  which  the  preparation  of  the  product  is 
completed,  without  regard  to  the  filling  of  final  con- 
tainers. 

Paragraph  2.  The  return  date  on  the  trade  labels  of 
anthrax  vaccine  prepared  by  the  Pasteur  method  shall  be 
a  date  not  more  than  3  months  later  than  that  on  which 
the  preparation  of  the  product  is  completed  without 
regard  to  the  filling  of  final  containers. 

SECTION  3.  The  immunity  unit  for  measuring  the 
strength  of  tetanus  antitoxin  shall  be  10  times  the  least 
quantity  of  antitetanic  serum  necessary  to  save  the  life 
of  a  350-gram  guinea  pig  for  96  hours  against  the  official- 
test  dose  of  the  standard  toxin  furnished  by  the  Hy- 
gienic Laboratory  of  the  United  States  Public  Health 
Service.  The  number  of  the  immunity  units  recom- 
mended for  the  prevention  of  tetanus  in  a  horse  shall 
be  at  least  500  units. 


296  HOG   CHOLERA 

REGULATION  21. — ADMISSION  OF  VIRUSES,   SERUMS,  TOXINS, 
AND  ANALOGOUS  PRODUCTS 

SECTION  1.  No  virus,  serum,  toxin,  or  analogous  prod- 
uct which  has  not  been  prepared,  handled,  stored,  and 
marketed  in  accordance  with  these  regulations,  and  no 
virus,  serum,  toxin,  or  analogous  product  which  is  worth- 
less, contaminated,  dangerous,  or  harmful  shall  be 
brought  on  to  the  premises  of  any  licensed  establish- 
ment. 

THE   VIRUS-SERUM-TOXIN   LAW 

[Extract  from  "An  act  making  appropriations  for  the  Depart- 
ment of  Agriculture  for  the  fiscal  year  ending  June  30,  1914," 
approved  March  4,  1913  (37  Stat.,  832).] 

That  from  and  after  July  first,  nineteen  hundred  and 
thirteen,  it  shall  be  unlawful  for  any  person,  firm,  or 
corporation  to  prepare,  sell,  barter,  or  exchange  in  the 
District  of  Columbia,  or  in  the  Territories,  or  in  any 
place  under  the  jurisdiction  of  the  United  States,  or  to 
ship  or  deliver  for  shipment  from  one  State  or  Territory 
or  the  District  of  Columbia  to  any  other  State  or  Terri- 
tory or  the  District  of  Columbia,  any  worthless,  contami- 
nated, dangerous,  or  harmful  virus,  serum,  toxin,  or 
analogous  product  intended  for  use  in  the  treatment  of 
domestic  animals,  and  no  person,  firm,  or  corporation 
shall  prepare,  sell,  barter,  exchange,  or  ship  as  aforesaid 
any  virus,  serum,  toxin,  or  analogous  product  manufac- 
tured within  the  United  States  and  intended  for  use  in 
the  treatment  of  domestic  animals,  unless  and  until  the 
said  virus,  serum,  toxin,  or  analogous  product  shall  have 
been  prepared,  under  and  in  compliance  with  regula- 
tions prescribed  by  the  Secretary  of  Agriculture,  at  an 
establishment  holding  an  unsuspended  and  unrevoked 
license  issued  by  the  Secretary  of  Agriculture  as  herein- 
after authorized.  That  the  importation  into  the  United 
States,  without  a  permit  from  the  Secretary  of  Agricul- 


APPENDIX  297 

ture,  of  any  virus,  serum,  toxin,  or  analogous  product 
for  use  in  the  treatment  of  domestic  animals,  and  the 
importation  of  any  worthless,  contaminated,  dangerous, 
or  harmful  virus,  serum,  toxin,  or  analogous  product  for 
use  in  the  treatment  of  domestic  animals,  are  hereby 
prohibited.  The  Secretary  of  Agriculture  is  hereby  au- 
thorized to  cause  the  Bureau  of  Animal  Industry  to  ex- 
amine and  inspect  all  viruses,  serums,  toxins,  and  analo- 
gous products,  for  use  in  the  treatment  of  domestic  ani- 
mals, which  are  being  imported  or  offered  for  importa- 
tion into  the  United  States,  to  determine  whether  such 
viruses,  serums,  toxins,  and  analogous  products  are 
worthless,  contaminated,  dangerous,  or  harmful,  and  if 
it  shall  appear  that  any  such  virus,  serum,  toxin,  or 
analogous  product,  for  use  in  the  treatment  of  domestic 
animals,  is  worthless,  contaminated,  dangerous,  or  harm- 
ful, the  same  shall  be  denied  entry  and  shall  be  destroyed 
or  returned  at  the  expense  of  the  owner  or  importer. 
That  the  Secretary  of  Agriculture  be,  and  hereby  is, 
authorized  to  make  and  promulgate  from  time  to  time 
such  rules  and  regulations  as  may  be  necessary  to  pre- 
vent the  preparation,  sale,  barter,  exchange,  or  shipment 
as  aforesaid  of  any  worthless,  contaminated,  dangerous, 
or  harmful  virus,  serum,  toxin,  or  analogous  product  for 
use  in  the  treatment  of  domestic  animals,  and  to  issue, 
suspend,  and  revoke  licenses  for  the  maintenance  of  es- 
tablishments for  the  preparation  of  viruses,  serums,  tox- 
ins, and  analogous  products,  for  use  in  the  treatment  of 
domestic  animals,  intended  for  sale,  barter,  exchange,  or 
shipment  as  aforesaid.  The  Secretary  of  Agriculture  is 
hereby  authorized  to  issue  permits  for  the  importation 
into  the  United  States  of  viruses,  serums,  toxins,  and 
analogous  products,  for  use  in  the  treatment  of  domestic 
animals,  which  are  not  worthless,  contaminated,  danger- 
ous, or  harmful.  All  licenses  issued  under  authority  of 
this  Act  to  establishments  where  such  viruses,  serums, 
toxins,  or  analogous  products  are  prepared  for  sale,  bar- 
ter, exchange,  or  shipment  as  aforesaid,  shall  be  issued 
on  condition  that  the  licensee  shall  permit  the  inspection 
of  such  establishments  and  of  such  products  and  their 


298  HOG   CHOLERA 

preparation ;  and  the  Secretary  of  Agriculture  may  sus- 
pend or  revoke  any  permit  or  license  issued  under  au- 
thority of  this  Act,  after  opportunity  for  hearing  has 
been  granted  the  licensee  or  importer,  when  the  Secre- 
tary of  Agriculture  is  satisfied  that  such  license  or  per- 
mit is  being  used  to  facilitate  or  effect  the  preparation, 
sale,  barter,  exchange,  or  shipment  as  aforesaid,  or  the 
importation  into  the  United  States  of  any  worthless, 
contaminated,  dangerous,  or  harmful  virus,  serum,  toxin, 
or  analogous  product  for  use  in  the  treatment  of  domes- 
tic animals.  That  any  officer,  agent,  or  employee  of  the 
Department  of  Agriculture  duly  authorized  by  the  Sec- 
retary of  Agriculture  for  the  purpose  may,  at  any  hour 
during  the  daytime  or  nighttime,  enter  and  inspect  any 
establishment  licensed  under  this  Act  where  any  virus, 
serum,  toxin,  or  analogous  product  for  use  in  the  treat- 
ment of  domestic  animals  is  prepared  for  sale,  barter, 
exchange,  or  shipment  as  aforesaid.  That  any  person, 
firm,  or  corporation  who  shall  violate  any  of  the  provi- 
sions of  this  Act  shall  be  deemed  guilty  of  a  misde- 
meanor, and  shall,  upon  conviction,  be  punished  by  a 
fine  of  not  exceeding  $1,000  or  by  imprisonment  not  ex- 
ceeding one  year,  or  by  both  such  fine  and  imprisonment, 
in  the  discretion  of  the  court. 


UNITED   STATES   DEPARTMENT   OF   AGRICUL- 
TURE, BUREAU  OF  ANIMAL  INDUSTRY 

AMENDMENT  1  TO  B.  A.  I.  ORDER  265 

Regulations  Governing  the  Preparation,  Sale,  Barter, 
Exchange,  Shipment,  and  Importation  of  Viruses, 
Serums,  Toxins,  and  Analogous  Products  Intended 
for  Use  in  the  Treatment  of  Domestic  Animals. 

Effective  on  and  after  August  1,  1920 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

OFFICE  OF  THE  SECRETARY, 
Washington,  D.  C.,  July  14,  1920. 
Under  authority  conferred  by  law  upon  the  Secretary 
of  Agriculture,  paragraph  2,  section  3,  Regulation  17  of 
B.  A.  I.  Order  265,  dated  August  1,  1919,  and  effective 
September  1,  1919,  is  hereby  revoked. 

Section  9,  Regulation  17,  is  amended  by  adding  thereto 
a  paragraph,  numbered  paragraph  5,  reading  as  herein- 
after set  forth. 

Paragraphs  2  and  3,  section  5,  Regulation  2 ;  paragraph 
7,  section  2,  Regulation  12 ;  paragraph  1,  section  3,  para- 
graph 2,  section  4,  (&)  paragraph  3,  and  (a)  and  (&) 
paragraph  4,  section  9,  Regulation  17 ;  paragraph  5,  sec- 
tion 5,  Regulation  18;  paragraph  2,  section  6,  (c)  para- 
graph 1,  section  8,  and  paragraph  3,  section  11,  Regula- 
tion 19 ;  and  paragraph  1,  section  2,  Regulation  20  of 
B.  A.  I.  Order  265,  are  hereby  amended  so  as  to  read  as 
hereinafter  set  forth. 

This  amendment,  for  the  purpose  of  identification,  is 
designated  Amendment  1  to  B.  A.  I.  Order  265,  and  shall 
become  and  be  effective  on  and  after  August  1,  1920. 

E.  D.  BALL, 

Acting  Secretary  of  Agriculture. 
299 


300  HOG   CHOLERA 

REGULATION   2. — LICENSES  AND  INSPECTIONS 

SECTION  5.  Paragraph  2.  Licenses  shall  be  numbered 
and  shall  be  in  the  following  form : 

UNITED  STATES  VETERINARY  LICENSE  No 

WASHINGTON,  D.  C., 

This  is  to  certify  that,  pursuant  to  the  terms  of  the  act 
of  Congress  approved  March  4,  1913  (37  Stat.,  832), 
governing  the  preparation,  sale,  barter,  exchange  ship- 
ment, and  importation  of  viruses,  serums,  toxins,  and 
analogous  products  intended  for  use  in  the  treatment  of 

domestic  animals,   is 

hereby  licensed  to  maintain  at 

an  establishment  for  the  preparation  or : 

This  license  is  subject  to  termination  as  provided  in 
the  regulations  made  under  the  authority  contained  in 
said  act  approved  March  4,  1913,  and  also  to  suspension 
or  revocation  if  the  licensee  violates  or  fails  to  comply 
with  any  provision  of  the  said  act  or  the  regulations 
made  thereunder. 


Secretary  of  Agriculture. 
Countersigned : 


Chief,  Bureau  of  Animal  Industry. 

SECTION  5.  Paragraph  3.  Should  a  licensed  establish- 
ment discontinue  the  production  of  any  virus,  serum, 
toxin,  or  analogous  product,  the  license  of  such  establish- 
ment shall  be  returned  to  the  bureau  for  termination  and 
a  new  license  issued  covering  such  products  named 
therein  as  the  establishment  shall  continue  to  produce. 
Should  an  establishment  be  engaged  in  the  preparation 
of  various  products  under  a  number  of  licenses  issued 
from  time  to  time  by  the  department,  the  licenses  shall 
be  returned  to  the  bureau  at  its  request  for  termination 
and  a  new  license  issued  covering  all  of  the  products 


APPENDIX  301 

embraced  in  the  returned  licenses  which  the  establish- 
ment shall  continue  to  produce. 

REGULATION  12. — LABELS 

SECTION  2.  Paragraph  7.  The  name  and  address  of 
the  manufacturer  may  be  omitted  from  trade  labels 
when  any  virus,  serum,  toxin,  or  analogous  product  is 
to  be  distributed  by  a  person  other  than  the  manufac- 
turer, but  in  such  case  the  distributor  must  state  on  the 
label  his  or  its  trade  name  and  address  in  immediate 
connection  with  a  statement  showing  the  license  under 
which  the  product  was  manufactured.  This  statement, 
together  with  the  name  and  address  of  the  distributor, 
shall  appear  in  letters  of  uniform  size  and  character 
and  be  in  the  following  form:  "Produced  under  U.  S. 

Veterinary  License  No. .   Distributed  by (name 

and  address  of  distributor)."  The  name  of  the  dis- 
tributor shall  not  appear  on  the  label  except  in  imme- 
diate connection  with  the  Federal  license  legend. 

REGULATION   17. — ANIMALS 

SECTION  3.  Paragraph  1.  All  hogs  which  are  admit- 
ted to  the  premises  of  licensed  establishments  under  the 
provisions  of  section  1,  paragraph  1,  of  this  regulation 
shall  be  held  in  receiving  pens  for  at  least  24  hours  after 
admission  to  the  premises,  and  during  this  time  they 
shall  be  allowed  free  range  and  contact  with  not  less 
than  2  contact  calves  for  each  lot  of  200  hogs  or  less  in 
the  receiving  pens. 

SECTION  4.  Paragraph  2.  The  removal  of  contact 
calves  from  receiving  pens  shall  be  so  arranged  that  a 
rotation  will  be  established  whereby  each  animal  will 
be  replaced  at  intervals  of  one  month  and  both  animals 
replaced  every  two  months. 

SECTION  9.  Paragraph  3  (&).  Hogs  which  survive 
inoculation  and  exposure  for  the  production  of  hog- 


302  HOG   CHOLEEA 

cholera  virus,  surviving  controls  from  tests  of  anti-hog- 
cholera  serum,  and  surviving  hogs  which  have  been  used 
for  testing  hog-cholera  virus  may  be  removed  from  the 
premises  of  the  establishment  not  sooner  than  15  days 
subsequent  to  the  day  of  inoculation  and  exposure,  pro- 
vided they  are  healthy.  It  is  required,  however,  that  all 
such  hogs  b'efore  their  removal  from  the  premises  be 
given  the  serum-alone  treatment  as  prescribed  under 
(a)  of  paragraph  4  of  this  section,  or  the  simultaneous 
treatment  prescribed  under  (&)  of  the  same  paragraph 
and  section.  Hyperimmune  hogs  and  pigs  used  for  test- 
ing the  purity  and  potency  of  anti-hog-cholera  serum 
may  be  removed  from  the  premises  of  licensed  establish- 
ments 21  days  subsequent  to  the  day  of  hyperimmuniza- 
tion  or  inoculation,  provided  they  exhibit  no  symptoms 
of  any  infectious,  contagious,  or  communicable  disease, 
and  provided  further  that  they  are  first  disinfected  as 
prescribed  in  paragraph  5  of  this  section.  Other  hogs 
shall  be  removed  from  the  premises  of  the  establishment 
only  after  treatment  and  disinfection  as  provided  in 
paragraph  5  of  this  section,  except  that  such  hogs  need 
not  be  held  21  days  when  treated  with  serum  and  virus 
which  have  been  released  for  marketing. 

SECTION  9.  Paragraph  4  (a).  Serum-alone  method. — 
The  serum  used  shall  have  been  prepared  and  released 
for  marketing  at  an  establishment  holding  a  license  from 
the  Secretary  of  Agriculture  and  the  dose  employed 
shall  conform  to  that  required  in  paragraph  1,  section  6, 
or  paragraph  3,  section  10,  of  Regulation  19.  After 
receiving  this  treatment  they  shall  be  disinfected  as  pre- 
scribed in  paragraph  5  of  this  section. 

SECTION  9.  Paragraph  4  (&).  Simultaneous-inocula- 
tion method. — The  serum  and  virus  used  shall  have  been 
prepared  at  an  establishment  holding  a  license  from  the 
Secretary  of  Agriculture  and  the  doses  shall  be  not  less 
than  those  required  in  paragraph  1,  section  6,  or  para- 


APPENDIX  303 

graph  3,  section  10,  of  Regulation  19.  After  receiving 
this  treatment  they  shall  be  held  under  the  supervision 
of  a  bureau  employee  for  a  period  of  at  least  21  days, 
except  when  treated  with  virus  and  serum  released  for 
marketing.  If  no  symptoms  of  hog  cholera  or  other  in- 
fectious, contagious,  or  communicable  disease  are  ex- 
hibited by  the  animals,  they  shall  be  disinfected  as  pre- 
scribed in  paragraph  5  of  this  section. 

SECTION  9.  Paragraph  5.  Before  removal  from  the 
premises  of  licensed  establishments  all  hogs  shall  be  dis- 
infected in  a  2  per  cent  aqueous  solution  of  cresol  com- 
pound, U.  S.  P.,  or  a  permitted  substitute  therefor,  and 
held  in  noninfectious  pens  for  a  period  of  at  least  three 
hours  before  being  loaded  for  transportation.  When 
the  temperature  of  the  air  is  below  freezing,  comfort- 
able quarters  shall  be  furnished  for  the  disinfected  ani- 
mals until  they  are  dry. 

REGULATION    18. — HOG-CHOLERA    VIRUS 

SECTION  5.  Paragraph  5.  Trade  labels  affixed  to  or 
used  in  connection  with  each  immediate  or  true  con- 
tainer of  simultaneous  virus  shall  bear  a  dosage  table 
in  which  the  doses  recommended  are  not  less  than  those 
appearing  in  the  following  table: 

Weight.  Minimum  Dose. 

Pigs  weighing  45  pounds  or  less 1  c.  c. 

Hogs  weighing  more  than  45  pounds 2  c.  c. 

REGULATION    19. — ANTI-HOG-CHOLERA   SERUM 

SECTION  6.  Paragraph  2.  Anti-hog-cholera  serum  the 
test  of  which  has  proved  it  to  be  "unsatisfactory,"  as 
defined  in  1  and  2  of  rule  C  of  this  regulation,  may  be 
tested  again  as  described  in  sections  4  and  5  of  this 
regulation.  Should  the  second  test  prove  to  be  "satis- 
factory, ' '  as  defined  in  rule  D,  the  serum  may  be  released 


304  HOG   CHOLEKA 

for  marketing  under  the  conditions  set  forth  in  para- 
graph 1  of  this  section.  If  the  test  is  again  found  "un- 
satisfactory," as  defined  in  1  and  2,  rule  C,  paragraph 
2,  section  5,  of  this  regulation,  the  serum  shall  not  be 
marketed  unless  and  until  it  is  either  concentrated,  re- 
fined, and  tested  in  a  manner  approved  by  the  chief  of 
bureau,  or  mixed  with  other  serum  and  tested  as  pro- 
vided in  section  7  of  this  regulation. 

SECTIONS.  Paragraph  1  (c) .  Anti-hog-cholera  serum 
which  has  been  found  "unsatisfactory  for  purity"  may 
again  be  tested  for  purity  upon  8  pigs,  provided  each 
pig  receives  a  single  injection  in  the  axillary  space  of  at 
least  20  c.  c.  of  the  product  to  be  tested.  Immune  pigs 
may  be  used  for  testing  the  purity  of  anti-hog-cholera 
serum  if  desired.  The  pigs  used  should  be  held  under 
the  supervision  of  a  bureau  employee  for  at  least  15 
days. 

SECTION  11.  Paragraph  3.  Should  the  return  date  of 
any  batch  of  anti-hog-cholera  serum  expire  before  the 
serum  is  used,  the  serum  should  be  retested,  and  if  found 
satisfactory  as  defined  in  rule  D,  paragraph  2,  section  5, 
of  this  regulation,  the  return  date  may  be  extended  one 
year  from  the  date  of  retest. 

REGULATION   20. — BACTERINS,    VACCINES,    TOXINS,    ETC. 

SECTION  2.  Paragraph  1.  The  return  date  on  the 
trade  labels  of  blackleg  vaccine  prepared  from  attenu- 
ated B.  chauveaui,  or  blackleg  muscle  virus,  shall  be  a 
date  not  more  than  one  and  one-half  years  later  than 
the  date  on  which  the  preparation  of  the  product  is 
completed,  without  regard  to  the  filling  of  final  con- 
tainers. 


UNITED  STATES  DEPARTMENT  OF  AGRICUL- 
TURE, BUREAU  OF  ANIMAL  INDUSTRY 

AMENDMENT  2  TO  B.  A.  I.  ORDER  265 

Regulations  Governing  the  Preparation,  Sale,  Barter, 
Exchange,  Shipment,  and  Importation  of  Viruses, 
Serums,  Toxins,  and  Analogous  Products  Intended 
for  Use  in  the  Treatment  of  Domestic  Animals. 

U.  S.  DEPARTMENT  OF  AGRICULTURE, 

OFFICE  OF  THE  SECRETARY, 
Washington,  D.  C.,  February  15,  1921. 
Under  authority  conferred  by  law  upon  the  Secretary 
of  Agriculture,  paragraphs  1  and  6,  section  2,  Regula- 
tion 12,  of  B.  A.  I.  Order  265,  dated  August  1,  1919,  and 
effective  September  1,  1919,  are  hereby  amended  to  read 
as  hereinafter  set  forth. 

Paragraph  7,  section  2,  Regulation  12,  of  Amendment 
1  to  the  above  order,  dated  July  14,  1920,  and  effective 
on  and  after  August  1,  1920,  is  hereby  revoked ;  said  rev- 
ocation, as  applied  to  anti-hog-cholera  serum  and  hog- 
cholera  virus,  to  be  effective  on  and  after  May  1,  1921 ; 
as  to  other  products  said  revocation  to  be  effective  on  and 
after  January  1,  1922.  Paragraph  8,  section  2,  Regula- 
tion 12,  of  B.  A.  I.  Order  265  will  accordingly,  on  and 
after  January  1,  1922,  be  designated  paragraph  7. 

Paragraph  1,  section  3,  Regulation  17,  of  Amendment 
1  of  the  above  order,  is  hereby  amended  to  read  as  here- 
inafter set  forth. 

This  amendment,  for  the  purpose  of  identification,  is 
designated  Amendment  2  of  B.  A.  I.  Order  265,  and 
shall  become  and  be  effective  on  and  after  March  1, 1921, 
except  as  provided  below. 

E.  T.  MEREDITH, 
Secretary  of  Agriculture. 
305 


306  HOG   CHOLERA 

REGULATION  12. — LABELS 

SECTION  2.  Paragraph  1.  Trade  labels  shall  bear  the 
true  name  of  the  product  contained  in  the  package,  and 
this  name  shall  be  identical  with  that  given  in  the  license 
under  which  the  product  is  prepared.  The  name  shall 
also  be  so  lettered  and  placed  as  to  give  equal  promi- 
nence to  each  word  composing  it.  Such  labels  shall  also 
bear  the  name  and  address  of  the  manufacturer,  and  the 
license  or  permit  number  assigned  by  the  department. 
The  license  number  and  permit  number  shall  be  shown 
in  either  of  the  following  forms,  respectively:  "IT.  S. 

Veterinary  License  No.  ,"  or  "U.  S.  Vet.  License 

No. ,"  and  "U.  S.  Veterinary  Permit  No. ,"  or 

"U.  S.  Vet.  Permit  No. ."  These  labels  shall  bear 

all  other  information  required  by  the  chief  of  the  bureau, 
and  may  also  bear  any  other  statement  not  false  or  mis- 
leading, and  which  has  been  approved  by  the  bureau. 

SECTION  2.  Paragraph  6.  When  any  virus,  serum, 
toxin,  or  analogous  product  is  prepared  by  a  licensed 
establishment,  or  imported  for  a  person  other  than  the 
one  to  whom  a  license  or  permit  has  been  issued,  and  the 
name  and  address  of  the  distributor,  as  well  as  that  of 
the  manufacturer,  is  to  appear  on  the  trade  labels  of  the 
containers  thereof,  a  statement  shall  be  made  on  the 
labels  indicating  that  the  virus,  serum,  toxin,  or  analo- 
gous product  is  distributed  by  such  person.  The  name 
and  address  of  this  person  shall  not  appear  in  any  form 
or  manner  indicating  that  the  distributor  is  the  pro- 
ducer of  the  product,  and  operating  under  the  license  as 
shown  on  the  label.  The  terms  " Distributor, "  "Dis- 
tributors," " Distributed  by,"  or  equivalent  terms  may 
be  used  if  prominently  placed  and  lettered,  in  connec- 
tion with  the  name  and  address  of  the  distributing  per- 
son, provided  the  same  are  not  used  so  as  to  be  either 
false  or  misleading.  Reference  to  the  distributing  per- 
son shall  be  made  by  name  and  address  only. 


APPENDIX  307 

The  preceding  paragraphs  1  and  6,  as  applied  to  anti- 
hog-cholera  serum  and  hog-cholera  virus,  shall  become 
and  be  effective  on  and  after  May  1,  1921;  as  to  other 
products  they  will  be  effective  on  and  after  January  1, 
1922. 

REGULATION  17. — ANIMALS 

SECTION  3.  Paragraph  1.  All  hogs  which  are  admit- 
ted to  the  premises  of  licensed  establishments  under  the 
provisions  of  section  1,  paragraph  1,  of  this  regulation, 
shall  be  held  in  receiving  pens  for  at  least  24  hours  after 
admission  to  the  premises,  with  the  exception  of  pigs 
which  are  used  in  testing  the  potency  and  purity  of 
anti-hog-cholera  serum,  in  which  case  6  hours  will  be 
sufficient ;  and  during  this  time  all  of  these  animals  shall 
be  allowed  free  range  and  contact  with  not  less  than 
2  contact  calves  for  each  lot  of  200  hogs  or  less  in  the 
receiving  pens. 


UNITED  STATES  DEPARTMENT  OF  AGRICUL- 
TURE, BUREAU  OF  ANIMAL  INDUSTRY 

AMENDMENT  3  TO  B.  A.  I.  ORDER  265 

Regulations  Governing  the  Preparation,  Sale,  Barter, 
Exchange,  Shipment,  and  Importation  of  Viruses, 
Serums,  Toxins,  and  Analogous  Products  Intended 
for  Use  in  the  Treatment  of  Domestic  Animals. 

Effective  on  and  after  April  1,  1922 

U.  S.  DEPARTMENT  OP  AGRICULTURE, 

OFFICE  OF  THE  SECRETARY, 
Washington,  D.  C.,  March  13,  1922. 
Under  authority  conferred  by  law  upon  the  Secretary 
of  Agriculture,  paragraphs  6,  8,  and  9,  section  4,  Regu- 
lation 18,  of  B.  A.  I.  Order  265,  dated  August  1,  1919, 
and  effective  September  1,  1919,  are  hereby  amended  so 
as  to  provide  that  three  pigs  immune  to  hog  cholera  may 
be  used  in  lieu  of  the  two  calves  prescribed  by  the  afore- 
mentioned paragraph  6. 

This  amendment,  which  for  the  purpose  of  identifica- 
tion is  designated  as  Amendment  3  to  B.  A.  I.  Order  265, 
shall  become  effective  on  and  after  April  1,  1922. 

C.   W.   PUGSLEY, 

Acting  Secretary  of  Agriculture. 


308 


INDEX 


Abortion,  due  to  simultaneous 
treatment,  146 

Abscesses,  following  serum 
injection,  135 

Absorption,  of  injected  serum, 
130 

Ante-mortem  inspection,  in 
outbreaks  of  hog  chol- 
era, 213 

Anthrax,  differentiating  hog 
cholera  from,  71 

Animal  inoculation,  in  diag- 
nosing hog  cholera,  67 

Ascarids,      as      a     cause      of 
' '  serum  breaks, ' '  144 

Ascaris  infestation,  confused 
with  hog  cholera,  72 

Autopsy,  of  virus  pig,  87 

Bact.   suisepticum,  as  a  com- 
plication   of    hog    chol- 
era, 21,  46,  47,  52 
hemorrhages  due  to,  53,  56 

Bladder,  hog  cholera  lesions 
in,  53 

Bleeding,  for  serum,  98 
the  virus  pig,  85 

B.  necrophorus,  complicating 
hog  cholera,  30,  43,  44, 
45,  47 

B.  pyocyaneus,  complicating 
hog  cholera,  27,  47 

B.  pyogenes  suis,  lesions  pro- 
duced in  swine,  33 

' '  Breaks, ' '  following  serum- 
virus  treatment,  18, 
140,  181,  182 

B.    suipestifer,     "button    ul- 
cers"  due  to,  45 
complicating     hog     cholera, 

25,  50,  52 
relation  to  hog  cholera,  3 


Buildings  required  for  serum 
preparation,  78 

Cecum,  hog  cholera  lesions  in, 
44 

Confinement,  of  hogs  for 
serum  treatment,  118 

Diagnosis,  of  hog  cholera,  58 

Diagnosis,  differential,  of  hog 
cholera,  68 

Disinfectants,  as  destroyers 
of  hog  cholera  virus, 
12 

Dissemination,  of  hog  chol- 
era, 17 

Dosage,   of   serum,   131 
of  serum  and  virus,  138 

Dose  table,  of  serum,  Bureau 
of  Animal  Industry, 
110 

Equipment,  for  serum  prepa- 
ration, 80 

Feeder  hogs,  handling  to  pre- 
vent hog  cholera,  180 
relation  to  hog  cholera  dis- 
semination, 236 

[Fees,  veterinarian 's,  for  serum 
administration,  191 

Filterable  virus,  the  cause  of 

hog  cholera,  4,   8 
disinfectants,  destroyers  of. 

12 

elimination  of,  following 
serum-virus  treatment, 
147 

heat  as  a  destroyer  of,   11 
putrefaction  as  a  destroyer 

of,  11 
virulence  of,  10 

"Flu,"  so-called,  differenti- 
ating from  hog  cholera, 
71 


309 


310 


INDEX 


Follow-up  treatment,  153 
Garbage     fed     swine     herds, 
veterinary      supervision 
of,  219 

Garbage  feeding,  as  a  means 
of  hog  cholera  spread, 
17,  214 

and       sanitary       considera- 
tions,   225 
licenses  for,  227 
municipal,  217,  218 
Heart,  hog  cholera  lesions  in, 

47 
Heat,   as   a   destroyer   of   hog 

cholera  virus,  11 
Hemorrhagic  septicemia,  rela- 
tion     to      '  '  s  e r  u  m 
breaks,"  149 

History,  of  outbreak,  in  rela- 
tion to  hog  cholera  di- 
agnosis, 58,  59 
Hog     cholera,     complications, 

21 
control   and   eradication  of, 

230 

diagnosis,  58 
diagnosis,  differential,  68 
economic  importance,  2 
forms  of,   35,   36 
handling  in  the  field,  158 
history  of,  1 
incubation  period  of,  35 
infected  herd,  handling,  161 
lesions  of,  40-56 
methods    of    dissemination, 

17 

nature  and  cause,  7 
prognosis,  74 
relation  to  garbage  feeding, 

214 
relation  to  meat  inspection. 

197 

symptoms,   35 
Hog  holder,  123 
Hyperimmune,  the,  89 
Hypering,  dangers  due  to,  95 

technique,  90 
Immunity,   of   young   pigs   to 

cholera,  8,  171,  172 
establishing  herd,  174 


Immunity,  active,  due  to  fol- 
low-up treatment,   155 
active,  due  to  simultaneous 

treatment,   138,   151 
passive,  due  to  serum  alone, 
127,  136 

Kidney,  hog  cholera  lesions 
in,  50,  51 

Label,  features  of  serum,  111 
features  of  virus,  116 

Larynx,  hog  cholera  lesions 
in,  45 

Legislation,  regarding  use  of 
serum  and  virus,  192, 
193 

Lesions,  of  hog  cholera,  40 
as  an  aid  in  diagnosing  hog 
cholera,  63 

Lungs,  hog  cholera  lesions  in, 
45 

Lung  worm  infestation,  con- 
fused with  hog  cholera, 
72 

Lymph  glands,  hog  cholera 
lesions  in,  54 

Lysol,  as  a  destroyer  of  hog 
cholera  virus,  15 

Marketing  hogs,  following 
serum  and  virus  treat- 
ment, 169 

Meat  inspection,  in  field  out- 
breaks of  hog  cholera, 
210 

relation   of  hog  cholera  to, 
197 

Mixed  infection,  in  swine,  33 

Mortality,  due  to  hog  chol- 
era, 7 

Mouth  and  pharynx,  hog 
cholera  lesions  in,  43 

Putrefaction,  as  a  destroyer 
of  hog  cholera  virus, 
11 

References,  243 

Eegulations,  meat  inspection. 
B.  A.  I.  relative  to  hog 
cholera,  199,  200 
relative  to  preparation  and 
sale  of  biologies  (B. 
A.  I.),  247 


INDEX 


311 


Binderpest,         differentiating 

from  hog  cholera,  74 
Eouget,    differentiating    from 

hog  cholera,  74 
Septicemia,     following    serum 

treatment,  134 

Serum,  anti-hog-cholera,  fees 
for  administering, 
191 

keeping  qualities,  114 
Serum,          anti  -  hog  -  cholera, 
methods  of  using,  118, 
126 

follow-up    method,    descrip- 
tion, 153 

indications  and   contrain- 
dications, 157 
serum  alone,  method,  127 
dangers  due  to,  133 
indications   and  contrain- 
dications, 137 
technique    of    administer- 
ing, 128 
therapeutic       value       of, 

133 

simultaneous  method,  137 
dangers,  139 
dosage     of     serum     and 

virus,  138 

indications  and  contrain- 
dications, 152 
technique  of,  138 
Serum,     anti-hog-cholera,     or- 
dering, 188 

anti-hog-cholera,       prepara- 
tion of,  76 
anti-hog-cholera,  testing, 

105 

bleeding  for,  98 
bottling  and  labeling,   111 
B.    A.    I.    Regulations    for, 

247 

clear  and  "bloody,"  112 

principle  involved  in,  82 

tail  and  carotid  bled,  113 

Serum   "breaks,"   preventing 

and  handling,  145 


Shipping,  as  a  cause  of  serum 

"breaks,"     142,     181, 

182 

Show   hogs,   handling   to  pre- 
vent hog  cholera,  185 
Site    of    injection,    choice   of, 

128 
Small    intestine,    hog    cholera 

lesions  in,   44 
Spirocheta    hyos,    relation    to 

hog  cholera,  33 
Spleen,  hog  cholera  lesions  in, 

47 
Swine    plague,    differentiating 

from  hog  cholera,  70 
in    cholera    immune    herds, 

25 
Stomach,   hog   cholera   lesions 

in,  43 
Stunting,  of  pigs,  as  a  result 

of    simultaneous    treat- 
ment, 146 

Symptoms  of  hog  cholera,  35 
as  related  to   diagnosis,   60 
Technique,  of  serum  adminis- 
tration,  128 
Temperature  readings,    as   an 

aid  in  diagnosis,  61 
Temperatures,    low,    influence 

on    hog    cholera    virus, 

12 
Trachea,    hog   cholera   lesions 

in,  45 
Tuberculosis,       differentiating 

from  hog  cholera,  71 
"Vaccination    Cholera,"    18, 

140 

Virus  "breaks,"  140,  147 
Virus  of  hog  cholera,  keeping 

qualities,  116 
labeling,  116 
manner    of    producing,    84, 

115 
Virus,   laboratory,  relation  to 

hog  cholera  spread,   18 
Virus  pig,  the,  84 
autopsy  of,  87 


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